V4L/DVB (3324): msp3400 audio handling bug fixes.

- Check capabilities for audio settings (volume, balance,
bass, treble, loudness, mute)
- added loudness support
- added missing VIDEO_AUDIO_BALANCE flags for v4l1 compatibility
- do not call msp_any_detect_stereo for non-autoselect chips to
retrieve the current stereo setting: that will temporarily mute
the sound. It is only needed when the stereo mode might be
changed, and for autoselect msp processors that do not periodically
need to update their stereo setting.
- do not wake up the thread if the standard did not change. Prevents
temporary audio drop-out if the standard is set to the same value.
- fix confused stereo detect code where V4L2_TUNER_SUB_STEREO and
V4L2_TUNER_MODE_STEREO values were used incorrectly.
- stereo mode reporting was broken (v4l2 value used to index a
string array expecting v4l1 mode values).
- do not set dsp register 0x30 in the 3410d thread: that register
does not exist for pre-'G' revision msp chips.

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