V4L/DVB (13310): uvcvideo: Return -EINVAL instead of -ENODEV in read()

-EINVAL is required by the V4L2 specification. -ENODEV is simply wrong
as the device exists.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>