audiopolicy: Implement DolbyAudioPolicy

Merge hardware/libhardware_legacy DolbyAudioPolicy modifications to
audiopolicy .

Change-Id: I390c0e36afe366dcbb078b57c4880f7c3cfc6da8
Change OMX_AUDIO_CodingDDP to OMX_AUDIO_CodingAndroidAC3

Change-Id: I8d7769874bbe82b7dd478d0309ee202545a2325d