V4L/DVB (4223): Add V4L2_CID_MPEG_STREAM_VBI_FMT control

V4L2_CID_MPEG_STREAM_VBI_FMT controls if and how VBI data is embedded in
an MPEG stream. Currently only one format is supported: the format designed
for the ivtv driver. This should be extended with new standard formats
(such as defined for DVB) in the future.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>