drm/msm: notify hpd status when audio codec is ready

HDMI connector should wait for audio codec status and notify
HPD status only in case that audio codec has been registered
successfully. Meanwhile move HPD notification to bridge enable
and disable instead of hotplug work. This ensures the correct
video and audio sequence.

Change-Id: I0dac915c8639bb881265a608016e9d37ec9a153c
Signed-off-by: Ray Zhang <rayz@codeaurora.org>