Audio HAL V7.1: Add latency modes definitions

Latency mode control on audio HAL streams is optional but mandated
if spatial audio with head tracking is supported over Bluetooth classic
audio link.

Currently defined latency modes are:
- Low: a playback latency compatible with headtracking round trip
  latency requriements
- Free: no specific requirement on playback latency.

Bug: 187446271
Test: make
Change-Id: I37442ebffc66946d17425c53ece2b0afd8189898
2 files changed