msm_fb: HDMI: Export interface for setting Audio info frame

The Audio InfoFrame contains information that allows for the format
of the digital audio streams to be identified more quickly via
out-of-band information and, for multi-channel uncompressed audio
provides channel allocation information for the sink device's speakers.
Currently audio info frame is hard coded to support 2-ch PCM. To Support
Multi channel PCM, correct channel allocation information has to be sent
to HDMI sink. So export the interface for setting audio info frame to
HDMI audio driver.

Change-Id: I7d0d5cf9f8792250bfd6e5eb003a8360ccb9707a
Signed-off-by: Kiran Kandi <kkandi@codeaurora.org>