iommu: Add certain iommu header files into msm-next

Some clients require these iommu files for their
compilation to proceed. Add these files temporarily
to unblock them.

Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Change-Id: I3aa0f89ed2d8502422df2ec9045e8bd9e12dce49