msm: mdss: hdmi: HDMI cable connection status and vote

Add HDMI cable connection status functionality to be used by
audio driver before starting the audio session and vote for
hdmi tx core to remain power on until the audio has completed
its processing.

Change-Id: I35d1bafff472da19e04aa44f4ac91b1c3c0349e1
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>