V4L/DVB (3663): Fix msp3400c wait time and better audio mode fallbacks

- The wait time until the first time the audio mode was detected was
  1+5=6 seconds instead of just 1 second (wrong statement order).
  msp3400c specific bug.
- Implemented audio mode fallback for msp3400c/d just like the msp3400g
  does automatically. E.g. fallback to stereo if no second language exists,
  etc.

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