sparc64: Initialize iommu_map_table and iommu_pool

Like legacy IOMMU, use common iommu_map_table and iommu_pool for ATU.
This change initializes iommu_map_table and iommu_pool for ATU.

Signed-off-by: Tushar Dave <tushar.n.dave@oracle.com>
Reviewed-by: chris hyser <chris.hyser@oracle.com>
Reviewed-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>