[automerger skipped] Merge "AudioMixer: Enable 5.1 based for fallback downmix" am: 580a0d5508 am: 92447b3f4f am: c90c222035 -s ours

am skip reason: Merged-In Ie093319c5fefc459165ae3d6c57b7836e8b625e5 with SHA-1 8514b930b1 is already in history

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/2556150

Change-Id: I2eb8eca2adf105fe63670af554aa5359b465301c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>