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: I8a8ce8dd45cbb1c8aa4c90d126b779fc3e88e731
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>