[media] coda: add coda_video_device descriptors

Each video device descriptor determines the name, callback ops, and input and
output formats on the corresponding video device. This simplifies coda_enum_fmt
and coda_try_fmt a bit and will simplify adding separate video devices for JPEG
codecs due to the slightly different behavior in the CodaDx6/CODA7542 case and
a separate hardware unit on CODA960.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>