dt-bindings: mailbox: qcom-ipcc: document the support for SA8255p

Add a compatible for the ipcc on SA8255p platforms.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Nikunj Kela <quic_nkela@quicinc.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>

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

@@ -25,6 +25,7 @@ properties:
     items:
       - enum:
           - qcom,qdu1000-ipcc
+          - qcom,sa8255p-ipcc
           - qcom,sa8775p-ipcc
           - qcom,sc7280-ipcc
           - qcom,sc8280xp-ipcc