iommu/arm-smmu: Pass arm_smmu_domain to internal functions

Keep the types consistent, all the callers of these functions already have
obtained a struct arm_smmu_domain, don't needlessly go to/from an
iommu_domain through the internal call chains.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v2-c86cc8c2230e+160bb-smmu_newapi_jgg@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>