[media] usbvision: fix standards for S-Video/Composite inputs

The standards supported by S-Video and Composite inputs are not
limited by PAL, so make it more generic.

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