ASoC: msm: 8974: Add support for backend dai for HDMI on 8974.

Add support for backend dai for HDMI use cases related to audio.
This will open the afe ports on HDMI, set hdmi configuration.

Change-Id: Iae1f8bb5312d961aad6ef227cbd546b41b480e88
Signed-off-by: Harmandeep Singh <hsingh@codeaurora.org>