arm64: Enable CMA

arm64: Enable CMA

arm64 bit targets need the features CMA provides. Add the appropriate
hooks, header files, and Kconfig to allow this to happen.

Cc: Will Deacon <will.deacon@arm.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 6ac2104debc235b745265b64d610237a6833fd53)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
Conflicts:
	arch/arm64/Kconfig

(cherry picked from commit 0a4b0f00f4c9cb80a0fb11b9e0f898f82745e370)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
Conflicts:
	arch/arm64/mm/dma-mapping.c