[media] tm6000: fix querycap and input/tuner compliance issues

- add device_caps support
- fix bus_info
- fix numerous tuner-related problems due to incorrect tests
  and setting v4l2_tuner fields to wrong values.
- remove (audio) input support from the radio: it doesn't belong
  there. This also fixed a nasty issue where opening the radio
  would set dev->input to 5 for no good reason. This was never
  set back to a valid TV input after closing the radio device,
  thus leaving it at 5 which is out of bounds of the vinput
  card array.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>