Merge "libaudiohal@aidl: Properly handle "legacy" r_submix case" into main am: 636a5b50

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/2825373



Change-Id: Id2dab6dc166a47b7b2e155dbb75ea3bc4a843be1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>