display: Properly handle NO_IOMMU case

 * Enable it by default for msm8660 too.

Change-Id: Icbd5de1e7f020285ff6101c34286ca8863b11040

Conflicts:
	libhwcomposer/hwc_copybit.cpp
overlay: Allocate from MM heap as a fallback

 * Not all devices support IOMMU yet, so use the MM heap as a fallback.
 * Enabled when NO_IOMMU is set

Change-Id: I9d9f3dffb92f5b4bf45422df0f66a40611943202
hwc: rotator is not supported on msm7x27a

Change-Id: I26fe237831eb6fa41968d5eb6a75938e6dc53183