SF: Add DisplayDevice::initiateModeChange

This CL creates DisplayDevice::initiateModeChange which calls
HWC::setActiveConfigWithConstraints. SF should call DisplayDevice
instead of directly calling HWComposer.
This is a step towards removing the cached display modes from
the HWComposer class.

Test: presubmit
Bug: 159590486
Change-Id: Id05d2eacbbb6ed335fe205231b85e8af9a8ccd91