Add DVBSky S960/S860 DVB-S2 adapter frontend support

dmesg:

[  511.909692] usb 1-1.1.3: dvb_usb_v2: found a 'DVBSky S960/S860' in warm state
[  511.909884] usb 1-1.1.3: dvb_usb_v2: will pass the complete MPEG2 transport stream to the software demuxer
[  511.909928] DVB: registering new adapter (DVBSky S960/S860)
[  511.912645] usb 1-1.1.3: dvb_usb_v2: MAC address: 00:17:42:54:96:0c
[  511.914043] DVB: Unable to find symbol m88ds3103_attach()
[  511.919550] usb 1-1.1.3: dvbsky_s960_attach fail.
[  511.924923] usbcore: registered new interface driver dvb_usb_dvbsky

Kernel driver is available:

kmod-dvb-usb-dvbsky - 4.4.106+3-1-56ef06674a2579d8488bcbf4fe98e926-3 - Say Y here to support the USB receivers from DVBSky.

Frontend is missing:

turris:~# zcat /proc/config.gz |grep -i m88d
# CONFIG_DVB_M88DS3103 is not set

Please, could you enable CONFIG_DVB_M88DS3103 in kernel?