SPARC64: Enable IOMMU bypass for IB

SPARC64: Enable IOMMU bypass for IB

This change enables IOMMU bypass for Infiniband devices to workaround
the rds-stress performance issue. The performance slowdown is only
seen with rds-stress test. This test generates rigorous amount of dma
map/unmap calls.  Investigation shows that somewhere IOMMU/ATU code
doesn't scale and appears to be a bottleneck.

This is for uek4 only and not for upstream. When IOMMU/ATU issue gets
resolved, this workaround will be reverted.

Orabug: 25573557

Signed-off-by: Tushar Dave <tushar.n.dave@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>