Merge "audio policy: create spatializer mixer only when needed" into tm-dev am: c1e26474

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/17860127



Change-Id: I2c746533e780a209e48bed971b7a8028635c7eda
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>