V4L/DVB (9160): v4l: remove vidioc_enum_fmt_vbi_cap

Remove the vidioc_enum_fmt_vbi_cap ops: it was scheduled for removal in
2.6.28 since the v4l2 specification says that V4L2_BUF_TYPE_VBI_CAPTURE should
not support VIDIOC_ENUM_FMT. It's also pretty pointless.

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