alsa_sound: add support for low latency playback and recording

b/6865729

- Add deep buffer output in config file
- Configure deep buffer output if flag
  AUDIO_OUTPUT_FLAG_DEEP_BUFFER is set,
  otherwise configure low latency output.
- Add support for low latency recording
- Enable low latency recording path with
  system property
- For 2 buffers and 2048 bytes, reduce
  PLAYBACK_LOW_LATENCY to 21.5 ms

Change-Id: I3c0d54fa473fe89df5a3924de483f16975f4000e
Signed-off-by: Iliyan Malchev <malchev@google.com>