Fix backend crash due to different states retrieved from the modem

I'm testing it on Quectel - EC20 modem with O2 SIM card.

If the interface is down, the call to API will fail with the following error:

ValidationError: 'disabled' is not one of ['locked', 'connected']

root@turris:/tmp/reforis-gsm# foris-client-wrapper -m lte -a get_settings                                                                                                                                            
Traceback (most recent call last):                                                                                                                                                                                   
  File "/usr/bin/foris-client", line 33, in <module>                                                                                                                                                                 
    sys.exit(load_entry_point('foris-client==1.0.4', 'console_scripts', 'foris-client')())                                                                                                                           
  File "/usr/lib/python3.10/site-packages/foris_client/client/__main__.py", line 177, in main                                                                                                                        
  File "/usr/lib/python3.10/site-packages/foris_client/buses/mqtt.py", line 358, in send                                                                                                                             
  File "/usr/lib/python3.10/site-packages/foris_client/buses/mqtt.py", line 350, in process_resp                                                                                                                     
  File "/usr/lib/python3.10/site-packages/foris_client/buses/base.py", line 69, in _raise_exception_on_error                                                                                                         
foris_client.buses.base.ControllerError__lte__get_settings: Controller error(s) has occured:                                                                                                                         
Traceback (most recent call last):                                                                                                                                                                                   
  File "/usr/lib/python3.10/site-packages/foris_controller/message_router.py", line 140, in process_message                                                                                                          
    self.validate(reply)                                                                                                                                                                                             
  File "/usr/lib/python3.10/site-packages/foris_controller/message_router.py", line 40, in wrapper                                                                                                                   
    res = function(*args, **kwargs)                                                                                                                                                                                  
  File "/usr/lib/python3.10/site-packages/foris_controller/message_router.py", line 76, in validate                                                                                                                  
    app_info["validator"].validate(message)                                                                                                                                                                          
  File "/usr/lib/python3.10/site-packages/foris_schema/validator.py", line 282, in validate                                                                                                                          
  File "/usr/lib/python3.10/site-packages/jsonschema/validators.py", line 314, in validate                                                                                                                           
jsonschema.exceptions.ValidationError: 'disabled' is not one of ['locked', 'connected']                                                                                                                              
                                                                                                                                                                                                                     
Failed validating 'enum' in schema['properties']['data']['properties']['devices']['items']['properties']['info']['properties']['state']:                                                                             
    {'enum': ['locked', 'connected']}                                                                                                                                                                                
                                                                                                                                                                                                                     
On instance['data']['devices'][0]['info']['state']:                                                                                                                                                                  
    'disabled'                                                                                                                                                                                                       
                                                                                                                                                                                                                     
Incorrect output. {'kind': 'reply', 'module': 'lte', 'action': 'get_settings', 'data': {'devices': [{'id': 'wwan0', 'apn': 'internet', 'auth': {'type': 'none'}, 'qmi_device': '/dev/cdc-wdm0', 'pin': 'unset', 'inf}

In my opinion, we should add a "disabled" state.