Make the VBI support work for PAL standards in addition to NTSC.

This work was sponsored by EyeMagnet Limited.

Thanks go out to Andy Walls for providing a CD containing test PAL/VBI captures
and to Steven Toth for providing a PVR-350 to do signal generation with.
Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>