ASoC: msm: Add HDMI hostless front end driver

Add ALSA HDMI hostless front end driver. It is used to configure
AFE to route audio sample from mic input to HDMI output. It is used
for internal loopback, where HOST doesn't send audio sample to the DSP.

Change-Id: I07020075a456795a632be5901c47e3f114a9f534
Signed-off-by: Alex Wong <waiw@codeaurora.org>