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
Merge branch 'CyanogenMod/cm-11.0'