[media] radio-timb: add device_caps support, remove input/audio ioctls

The audio and input ioctls are not applicable for radio devices,
remove them.
Also set the device_caps field in v4l2_querycap.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Richard Röjfors <richard.rojfors@pelagicore.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>