Audio : Fix minor comments in r_submix module am: 7770c158

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



Change-Id: Ibae793a178e5ff3243a3d3db57672b60af1b2c0d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>