iommu/io-pgtable-arm: Simplify bounds checks

We're merely checking that the relevant upper bits of each address
are all zero, so there are cheaper ways to achieve that.

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

drivers/iommu/io-pgtable-arm.c

@@ -491,8 +491,7 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
 	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
 		return -EINVAL;
 
-	if (WARN_ON(iova >= (1ULL << data->iop.cfg.ias) ||
-		    paddr >= (1ULL << data->iop.cfg.oas)))
+	if (WARN_ON(iova >> data->iop.cfg.ias || paddr >> data->iop.cfg.oas))
 		return -ERANGE;
 
 	prot = arm_lpae_prot_to_pte(data, iommu_prot);
@@ -663,7 +662,7 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
 	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
 		return 0;
 
-	if (WARN_ON(iova >= (1ULL << data->iop.cfg.ias)))
+	if (WARN_ON(iova >> data->iop.cfg.ias))
 		return 0;
 
 	return __arm_lpae_unmap(data, gather, iova, size, lvl, ptep);