hammerhead: Make audio not suck anymore.

 * Add support for additional low-power offload modes
 * Enable gapless playback support
 * Enable 24-bit playback
 * Enable the compander for increased dynamic range on headphones
   and speaker output

Change-Id: If8cae7e940ba753d8b155017b15239bb49616b72

Conflicts:
	BoardConfig.mk
	audio_policy.conf
	device.mk