Merge changes from topic "enhance_hearing_aid"

* changes:
  audio: use SinkMetaData to route voice call with hearing aid.
  audio: Enhance latency and tuning in voice call with hearing aid
tree: 6cc05d9a91b6dbfd49354d48abc54af437965994
  1. hal/
  2. legacy/
  3. post_proc/
  4. visualizer/
  5. voice_processing/
  6. Android.mk
  7. OWNERS