iommu/arm-smmu: Convert to domain_alloc_paging()

iommu/arm-smmu: Convert to domain_alloc_paging()

Now that the BLOCKED and IDENTITY behaviors are managed with their own
domains change to the domain_alloc_paging() op.

The check for using_legacy_binding is now redundant,
arm_smmu_def_domain_type() always returns IOMMU_DOMAIN_IDENTITY for this
mode, so the core code will never attempt to create a DMA domain in the
first place.

Since commit a4fdd9762272 ("iommu: Use flush queue capability") the core
code only passes in IDENTITY/BLOCKED/UNMANAGED/DMA domain types. It will
not pass in IDENTITY or BLOCKED if the global statics exist, so the test
for DMA is also redundant now too.

Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/0-v1-3632c65678e0+2f1-smmu_alloc_paging_jgg@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>