display: Properly handle NO_IOMMU case

 * Enable it by default for msm8660 too.

Change-Id: Icbd5de1e7f020285ff6101c34286ca8863b11040
display: Various cleanups, fix legacy camera heap

 * Add explicit support for camera heap, if requested
 * Bring in line with kk_2.7
 * Don't push to MM heap for NO_IOMMU for display buffers
Change-Id: I30a8280099aa82e9b3e9754a4a68ad6a81f705f7
enable no iommu for 7x27a too