Change flush_unmaps() to correctly pass iommu_flush_iotlb_psi()
dma addresses.  (x86_64 mm and dma have the same size for pages
at the moment, but this usage improves consistency.)
Signed-off-by: NOmer Peleg <omer@cs.technion.ac.il>
[mad@cs.technion.ac.il: rebased and reworded the commit message]
Signed-off-by: NAdam Morrison <mad@cs.technion.ac.il>
Reviewed-by: NShaohua Li <shli@fb.com>
Reviewed-by: NBen Serebrin <serebrin@google.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>