iommu/amd: Limit the IOVA page range to the specified addresses

The extent of pages specified when applying a reserved region should
include up to the last page of the range, but not the page following
the range.

Signed-off-by: Gary R Hook <gary.hook@amd.com>
Fixes: 8d54d6c8 ('iommu/amd: Implement apply_dm_region call-back')
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>