mm-video: iommu: Fix decoding for devices without IOMMU (e.g some 8660)

This tells decoder to use MEM_ID/MM_HEAP instead of IOMMU

To use this functionnality, put this flag in BoardConfig:
TARGET_NO_IOMMU := true

Change-Id: I7fb039b2e0c3f9da2513c121d390cd3cac2b1a84