dt-bindings: arm-smmu: Add sc7180 compatible string

This patch simply adds a new compatible string for SC7180 platform.

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
Link: https://lore.kernel.org/r/1588329036-18732-2-git-send-email-smasetty@codeaurora.org


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