msm_fb: display: HPD rework for cleaner approach

Currently HPD is turned on and off with HDMI turn on and off
and turned on again after HDMI off so as to detect the cable
plugin.
With this change, HPD will be turned on when HDMI drvier is
initialized and turned off and on with suspend - resume. The
HPD handling during HDMI turn on and off has been removed.

CRs-Fixed: 368865
Change-Id: I1fb42b4587e58086d643b87a1600ecf09754423d
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>