sparc64: Enable PCI IOMMU version 2 API

Enable Version 2 of the PCI IOMMU API needed for advanced features
such as PCI Relaxed Ordering and greater than 2 GB DMA address
space per root complex.

Signed-off-by: Chris Hyser <chris.hyser@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>