V4L/DVB (5307): Add support for the cx23415 MPEG decoding features.

The cx23415 adds some extra features that this DVB decoding API did
not support. This API has been expanded to support the required
features. Both source and binary backwards compatibility is kept
intact by these changes. So existing applications are not affected.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Ralph Metzler <rjkm@metzlerbros.de>
Signed-off-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>