iommu: msm: add snapshot of msm_iommu.c

In preparation to port legacy iommu driver, add
snapshot of msm_iommu.c from msm-3.14's following
baseline

    dd5a662cfc73139642c1e0fab82d0160bc5b8248 (Merge "msm: ion:
    Define the source and destination vm parameters as u32")

Change-Id: I1b999d1494593c4bd1ca0d2351149eaee7c27abf
Signed-off-by: Shiraz Hashim <shashim@codeaurora.org>