This is a minor update to sba_iommu initialization code.  I moved the
relaxed ordering to the zx1 specific init routine, those registers don't
do anything on sx1000.  The iommu page size setup is more generalized on
ACPI ID, so the sx1000 specific init routine goes away.  And the virtual
dma_mask on zx1 was tweaked a little to better reflect the memory
address space.