AudioStreamOut: Align with AudioStreamIn

Currenty the MixerThread bypasses AudioStreamOut::getPresentationPosition so
inaccuracy in handling is avoided.  Fix this to work for the linear PCM
case.

Test: atest AudioTrackTest (with and without AudioStreamOut usage)
Bug: 326134469
Merged-In: I630d1e79bd591e6ce5e99ccec1df094e989be2f1
Change-Id: I630d1e79bd591e6ce5e99ccec1df094e989be2f1
1 file changed