Sound Control: fix register issue when fighting with HTC AudioHAL (rev 2)

HTC's Closed Sourced AudioHAL was doing something funky to their own shadow
registers which caused 1 of amps to be turned off when enabling another one.

Fixed a critical memory corruption derp on my part :( and added mutex
protections to prevent race conditions (making the updates atomic)

The original simplistic hacking force wasn't strong enough against the darkside
that is the HTC AudioHAL :p  Deep magic was needed to fully penetrate and
achieve its intended goal ;)

Bump to version 2.1 to indicate this update

Signed-off-by: faux123 <reioux@gmail.com>