libhardware: Add APIs to support DirectTrack

 -Add APIs in HAL to support Low Power Audio
  playback and Tunnel Audio playback.

Change-Id: Ic9d595e599c3222e2535745a8f1ebfb018ef75ed
(cherry picked from commit 4af9447d1c37f117463e2855fec845adaa299737)
(cherry picked from commit 6c2165c00805016ad5b4c2af3ac4ebfb49fd9170)
(cherry picked from commit c15cb2d03a371314c922588562a3e8a9f7238c08)

Conflicts:
	include/hardware/audio.h