CEC: Replace determistic mute commands

Compatibility issues on deterministic mute control commands
<MUTE_FUNCTION>/<RESTORE_AUDIO_VOLUME> are hard to get around.
This CL falls back to going with a non-deterministic one <MUTE>.

Bug: 24986703
Change-Id: Ia4cc0cf5ce6846a8d3bfbe638487b76a9986de89
(cherry picked from commit bae1d89e5734c9a4341681712deb63213b0b8452)