Preference multichannel pcm direct output over stereo mixer am: ecbf2ee4

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/19217565



Change-Id: I9884ad0e1e3888a68c96efa29c7f504f1b76d3b2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>