Audio : Fix minor comments in r_submix module am: 7770c158a1 am: f0506fad7e am: 41d85448d0 am: 2d057fc837

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

Change-Id: I263bf7aee2558246fc81e105da1f570bf69afc8f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>