msm: mdss: hdmi: Remove ext-5v gpio for HPD

Remove the PMIC's interface to 5V enable GPIO which is used to
enable power for HDMI HPD (Hot Plug Detect). This PMIC GPIO will
be used as HDMI voltage regulator so that multiple clients can
make use of it.

Change-Id: Ifd50344ce19541a1c055b9123c55eddd08ccd05f
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>