ARM: highbank: add coherent DMA setup

Some highbank DMA masters can support coherent (ACP) or non-coherent DMA.
This sets up dma_map_ops for masters which are configured for coherent DMA.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>