otter-common: Fix up use of FFMPEG codecs

Change-Id: I95a705365328f3329a741b5f4ed2ff39bdd7fbb2
otter: update audio_policy.conf

- remove deep_buffer
- add submix modules with 48000 sampling rates

Change-Id: Ia288ade014ec496c0e475116d20df01185a569dd