msm: mdss: hdmi: request DDC GPIOs when cable presence is confirmed

Currently GPIOs required for DDC transaction are requested when hpd
circuitry is turned on. But these GPIOs are needed only for EDID fetch
and HDCP authentication which can happen only when cable presence has
been confirmed. Create new DDC power module in order request these
GPIOs only when cable presence is confirmed. This change enables
alternate use of these GPIOs in non-hdmi debug use-cases.

CRs-Fixed: 478955
Change-Id: I67229d88eb92e39bc82fca0397fa9e13ad51c87b
Signed-off-by: Ujwal Patel <ujwalp@codeaurora.org>