iommu: Allocate dma-remapping structures using numa locality info

Allocate dma-remapping structures using numa locality info. On platforms
having remapping hardware units span different nodes, this enables
optimized dma-remapping transalation structures access by remapping hardware.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>