aaudio: control MMAP mode using system properties

To facilitate testing of MMAP mode.

Bug: 38268547
Test: set properties, see framesPerBurst in write_sine_callback.cpp
Change-Id: I6e15c563215017f6a5020d89ac312ff8331afc4f
Signed-off-by: Phil Burk <philburk@google.com>
6 files changed