audioserver: enable AAudioService for MR1

Another CL in OC-DEV may have turned it off.
This was added to resolve merge conflicts and to
only enable AAudioService when supported by the vendor.

Bug: 65280854
Bug: 65262790
Test: Enter  adb shell setprop aaudio.mmap_policy 1
Test: Enter  adb shell killall audioserver
Test: Enter  adb shell dumpsys media.aaudio
Test: It should print "Can't find service: media.aaudio".
Test: Enter  adb shell setprop aaudio.mmap_policy 2
Test: Enter  adb shell killall audioserver
Test: Enter  adb shell dumpsys media.aaudio
Test: It should print a short dump because the service is running.

Change-Id: Ic68d136c99c16134aa704495311ab25285fd76a9