V4L/DVB (3580): Last round of msp3400 cleanups before adding routing commands

Lots of cleanups:
- remove duplicate actions
- add D/K3 Dual FM-Stereo and D/K NICAM FM (HDEV3) support
- put prescales in the proper place
- add missing D/K NICAM
- msp34xxg_reset now only resets instead of also starting the autodetect
  (moved that to msp34xxg_thread)
- fix support for SAP.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>