V4L/DVB: cx18/cx25840/saa7115/tvp5150: remove vbi support from s_fmt

Now that s_fmt is no longer used for VBI format setup in subdevs, remove
the VBI support from s_fmt.

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