iommu: convert iommu_{un)map_range and dma_supported stub to static inline

Convert iommu_map_range and iommu_unmap_range to be static inline
stubs. Also fix the dma_supported APIs in the same manor.

Change-Id: I7c5c71efa0b4614f9c765b7fe2686555d0d3dfa1
Signed-off-by: Abhimanyu Kapur <abhimany@codeaurora.org>