iommu/arm-smmu-v3: Support 52-bit virtual address

Stage 1 input addresses are effectively 64-bit in SMMUv3 anyway, so
really all that's involved is letting io-pgtable know the appropriate
upper bound for T0SZ.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>