V4L/DVB (3271): more cleanups, simplify volume/balance/bass/treble ha…

…ndling

- Continue cleanup effort:
- more cosmetic changes
- combine volume, balance, bass and treble into one audio
function. Revert old 2.4 code that crept in.
- print internal ioctls using new debug function.
- marked all msp3400c (aka manual) functions as such.
- removed some unused data structures.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>