FROMLIST: iommu: Export core IOMMU functions to kernel modules

IOMMU drivers that can be compiled as modules need to use
some of the IOMMU core functions, so expose them.

Change-Id: I84004fdcd7eee3f56d08db76c3b0421990179810
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
Bug: 140290589
Link: https://patchwork.kernel.org/patch/10948413/