hal: Add support for HFP feature

 - Add set_parameters to be set from hfp app to enable
   and disable hfp session.
 - Implement start and stop hfp session which takes
   care of switching device and setting the session

Change-Id: Ie8697328ccbfee09d0d162f6fad01ddb552e4f83
7 files changed
tree: 0f9a5cc5e9e5d449a5c52672f5ddcc66ccc7ab18
  1. hal/
  2. legacy/
  3. visualizer/
  4. voice_processing/
  5. Android.mk