hal: Add support for Backend port specific channel map

Currently, channel map mixer control is generic for all
backend playback. Add support for backend device specific
mixer control to avoid overwrite of channel map configuration.
Also, always set proper channel map/allocation for playback
for HDMI and display port.

Change-Id: I41e3db6e07be869d82bdd3712744a5b78a707228
3 files changed