sound: Enable audio thru dock devices by default

 * This should just work. A user should not be expected to dig thru
   settings in order to make their shiny new dock play some Monster
   Magnet. Turn it on by default.

Change-Id: I7a8f4fd64831e2e7206046fa2af51589060d3383
Merge "sound: Enable audio thru dock devices by default" into jb-mr2