dma-mapping: replace set_arch_dma_coherent_ops with arch_setup_dma_ops

dma-mapping: replace set_arch_dma_coherent_ops with arch_setup_dma_ops

set_arch_dma_coherent_ops is called from of_dma_configure in order to
swizzle the architectural dma-mapping functions over to a cache-coherent
implementation. This is currently implemented only for ARM.

In anticipation of re-using this mechanism for IOMMU-backed dma-mapping
ops too, this patch replaces the function with a broader
arch_setup_dma_ops callback which will be extended in future.

Acked-by: Arnd Bergmann <[email protected]>
Acked-by: Marek Szyprowski <[email protected]>
Tested-by: Robin Murphy <[email protected]>
Signed-off-by: Will Deacon <[email protected]>