Change audio flinger to user HAL master mute if available

Hand merge from ics-aah

> Change audio flinger to user HAL master mute if available: DO NOT MERGE
>
> Replicate the pattern used for HAL master volume support to make use
> of master mute support if the HAL supports it.  This is part of the
> change needed to address bug 6828363.  Because of the divergences
> between ICS and master, this change will need to be merged by hand.
>
> Signed-off-by: John Grossman <johngro@google.com>
> Change-Id: I6d83be524021d273d093bcb117b8f2fe57c23685

Change-Id: I32280582905c969aaec2bb166ec5c61df82d737a
Signed-off-by: John Grossman <johngro@google.com>