Document compatible for the SCM firmware interface on SAR2130P platform.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20241017-sar2130p-scm-v1-1-cc74a6b75c94@linaro.org


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