V4L/DVB (5497): Additional card support for bttv driver

SSAI (www.ssai.us) makes several Bt878-based capture cards that get used in our
surveillance, conferencing, and medical imaging systems.  The attached
relatively small patch adds support for these cards, which fall into two broad
* boards with one or more Bt878s, one or more composite inputs, and no S-video
  or tuner inputs
* boards with one Bt878, one composite input, one S-video input, and no tuner
  input

Signed-off-by: Scott Alfter <salfter@ssai.us>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>