msm: mdss: hdmi: enable hpd interrupts for hdmi primary

HDMI as primary will also be HPD interrupt based. Update
user space with cable connect/disconnect notifications.
Enable DDC power as done normally in HPD interrupt handling.

Change-Id: I96b63be5877f1cde38604bc4cdb2dfcdc674cb8f
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>