audio policy manager: invert SPDIF/HDMI priority

Route media audio in priority to S/PDIF output when available
even if HDMI is connected. This allows users to chose to output audio
to a different system than the display.

Also force media volume to max when playing over S/PDIF.

Change-Id: I03b82a7235cb60f2b5d6cf7923570554b07ac400
1 file changed