iommu/arm-smmu: Wire up generic configuration support

With everything else now in place, fill in an of_xlate callback and the
appropriate registration to plumb into the generic configuration
machinery, and watch everything just work.

Change-Id: I7266b45b9795f5372da3349ed236a854d52a2fee
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Git-commit: 021bb842
Git-repo: https://source.codeaurora.org/quic/la/kernel/msm-4.4


Signed-off-by: Patrick Daly <pdaly@codeaurora.org>