Return interfaces on Turris 1.x on TOS 6.0
Since kernel 5.4 in TOS 6.0, /sys/firmware/devicetree/base/model now contain string Turris 1.x (from DTS).
On TOS 5.x it was just Turris.
Update the get_model() logic to detect Turris 1.x routers on TOS 6.0.