arm64: Use bus notifiers to set per-device coherent DMA ops

arm64: Use bus notifiers to set per-device coherent DMA ops

Recently, the default DMA ops have been changed to non-coherent for
alignment with 32-bit ARM platforms (and DT files). This patch adds bus
notifiers to be able to set the coherent DMA ops (with no cache
maintenance) for devices explicitly marked as coherent via the
"dma-coherent" DT property.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 6ecba8eb51b7d23fda66388a5420be7d8688b186)
Signed-off-by: Mark Brown <broonie@linaro.org>