[media] av7110: fix v4l2_compliance test issues

Besides the usual inconsistencies in input enumeration there was also a
kernel crash if you tried to poll on a vbi node. The checks for sliced
vbi output vs vbi capture were not complete enough.

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