msm: mdss: hdmi: handle HPD disconnect event during suspend

On device suspend, HDMI fb node is powered down. If HDMI cable is
now disconnected in suspend state, even though DISCONNECT event is
notified to display HAL to close HDMI fb node, fb driver early
returns since this fb node is already powered off. As a result,
HPD polarity is never configured to detect HPD high (connect) and
no subsequent HPD connections will be ever detected.
So on receiving HPD Disconnect event, configure HPD polarity to
detect HPD High if HDMI panel is already powered off.
Also make sure no HPD event is notified if same event is already
notified and waiting for completion.

Change-Id: I839b07f39eb5c2c24c249260cb482ae39b9bc771
Signed-off-by: Narender Ankam <nankam@codeaurora.org>