[media] v4l2-ctrls: V4L2_CTRL_CLASS_FM_RX controls are also valid radio controls

The radio filter function that filters controls that are valid for a radio
device should also accept V4L2_CTRL_CLASS_FM_RX controls.

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