Revert "Revert "hammerhead: Enable deep buffer output as primary""

 * This is working as intended now. Tested with Hangouts and other apps.
 * The purpose of this change is so that media playback uses the deep
   buffer path instead of the low-latency path, which uses much more
   power.

This reverts commit 22dde6a88e7b5453f39d96a23c65a3cd5d4dc085.

Change-Id: I476dd429be4b7c74acd888169004ed89081597c7