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

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

Change-Id: I4e38aad49e548070af5ba498c6426a8e01482097
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>