Merge "Downmix Effect: Fix processed samples" into main am: 9afbd388

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/2908798



Change-Id: I3b273285d78ff247311a115107e73d8544fd10c8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>