arm64: Implement set_arch_dma_coherent_ops() to replace bus notifiers

Commit 6ecba8eb (arm64: Use bus notifiers to set per-device coherent
DMA ops) introduced bus notifiers to set the coherent dma ops based on
the 'dma-coherent' DT property. Since the generic of_dma_configure()
handles this property for platform and AMBA devices, replace the
notifiers with set_arch_dma_coherent_ops().

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>