Where a device driver has set a 64-bit DMA mask to indicate the absence
of addressing limitations, we still need to ensure that we don't
allocate IOVAs beyond the actual input size of the IOMMU. The reported
aperture is the most reliable way we have of inferring that input
address size, so use that to enforce a hard upper limit where available.

Fixes: 0db2e5d1 ("iommu: Implement common IOMMU ops for DMA mapping")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>