hwc: Add load based partial mdp comp

Add support for load based partial mdp comp.
This is used on geometry changes where a redraw is unavoidable.
We select a batch of layers, that has minimum pixels for FB comp,
the rest go to MDP.

Conflicts:
	libhwcomposer/hwc_utils.cpp
	libhwcomposer/hwc_utils.h

Change-Id: Ifc5eeb4785c75c37de97a2bb89ca81409d324691
4 files changed