Add support for mt8192 SCP.

Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
Reviewed-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20200921094847.2112399-1-pihsun@chromium.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>