iommu/arm-smmu: Remove some duplicate macro definitions

When we brought back hardware ATOS support [94bc8904:
"iommu/arm-smmu: Resurrect hardware iova-to-phys"] we added some macros
back that were never deleted in the first place.  Clean up the redundant
macros.

Change-Id: I0129313fa4132f45fe5805e9ed3477ef7819e70e
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>