arm64: Add mmu context save/restore APIs

New API required by sdm845 DDR init/training protocol

TEST=build & run

Change-Id: I8442442c0588dd6fb5e461b399e48a761f7bbf29
Signed-off-by: T Michael Turney <mturney@codeaurora.org>
Reviewed-on: https://review.coreboot.org/25818
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
2 files changed