drm/msm/dp: add support for dp power

Add a module which configures the power related resources
for DisplayPort. Provide an API that can be called by the
DisplayPort driver to get the functionalities of power
module. Configure gpio/pinctrl/regulators/clock based on
the functionalities called by the DisplayPort driver.

Change-Id: I89b611199c31af92d0a44b43b0b25363c841a452
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>