Let the IOMMU core know we support arbitrary page sizes (as long as
they're an order of 4KiB).

This way the IOMMU core will retain the existing behavior we're used to;
it will let us map regions that:
- their size is an order of 4KiB
- they are naturally aligned
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Cc: Joerg Roedel <Joerg.Roedel@amd.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>