AudioService: undock audio glitch - DO NOT MERGE

merge from master:

"AudioService: improve low end dock audio control

Low end docks have a menu to enable use of audio
for media: automatically enabling/disabling use of audio
when the dock is connected/disconnected is useless
and can be the source of audio glitches.

Bug 7463620."

Change-Id: I3b7e7ebe660bb3f0e4367d2a3ed63ee76f78fe58