Audio : Fix minor comments in r_submix module am: 7770c158a1 am: f0506fad7e am: 41d85448d0

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2664716

Change-Id: I1246a31f1545932c0f8af93cf16296b6938b8379
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>