dt-bindings: mailbox: qcom-ipcc: Add compatible for SM8550

Document the compatible for SM8550 mailbox.
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

Documentation/devicetree/bindings/mailbox/qcom-ipcc.yaml

@@ -31,6 +31,7 @@ properties:
           - qcom,sm8250-ipcc
           - qcom,sm8350-ipcc
           - qcom,sm8450-ipcc
+          - qcom,sm8550-ipcc
       - const: qcom,ipcc
 
   reg: