arm64: Implement coherent DMA API based on swiotlb

This patch adds support for DMA API cache maintenance on SoCs without
hardware device cache coherency.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 7363590d2c4691593fd280f94b3deaeb5e83dbbd)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
4 files changed