sparc/leon: Add LEON dma_ops.

This patch sets the dma_ops structure for LEON. It reuses the pci32_dma_ops.

Signed-off-by: Kristoffer Glembo <kristoffer@gaisler.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>