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: I2ff184e0d62a3721d8645681a2c9251df0490830
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>