[media] usbvision: remove g/s_audio and for radio remove enum/g/s_input

The g/s_audio ioctls didn't do anything, so remove them all for both
video and radio nodes and remove V4L2_CAP_AUDIO.

The enum/g/s_input ioctls are invalid for radio nodes, so remove them
from the radio ioctl_ops.

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