[media] saa7164: fix format ioctls

Fix various v4l2-compliance issues in the formatting ioctls:

- the vbi device implemented video format ioctls which make no senses
  for a vbi device, remove them.
- remove the unused ts_packet_size and ts_packet_count fields.
- fill in colorspace and field.
- fill in sizeimage with a default value.
- for the video node the get, set and try format functions all do the
  same thing, so combine into a single function.

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