Merge "libeffects: Fix processed samples for downmix effect" into main am: ecde86a4

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/2897611



Change-Id: Ie3706d993f8ccc0417c75371fa38912a30fea7b0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>