dt-bindings: firmware: scm: Add compatible for SDX55

Add devicetree compatible for SCM present in SDX55 platform.

Acked-by: Rob Herring <robh@kernel.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20210408170457.91409-7-manivannan.sadhasivam@linaro.org


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