V4L/DVB (5182): Remove #if 0 section from videodev2.h

Remove a section containing basically ideas for future sliced VBI standards.
This can be resurrected should any of this be actually implemented. For now
it only pollutes this header file.

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