Audio HAL server needs to set SCHED_FIFO scheduling policy
for its threads that communicate with FastMixer threads of
AudioFlinger that use the same scheduler.

Bug: 30222631
Change-Id: I405a69d097a6bfed455e3483365b27c4004e1063

Bug: 32123421
Bug: 32905206

Test: compiles, nfc works
Change-Id: Ibf72ef70255573e4df0863ea640354b3c37eb47d

Bug: 32123421
Test: build Hikey
Change-Id: Iaf02626f3f3a94104c0f9d746c3cf5f20751a27d