dt-bindings: mailbox: qcom-ipcc: document the sa8775p platform

Add a compatible for the ipcc on sa8775p platforms.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

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

@@ -24,6 +24,7 @@ properties:
   compatible:
     items:
       - enum:
+          - qcom,sa8775p-ipcc
           - qcom,sc7280-ipcc
           - qcom,sc8280xp-ipcc
           - qcom,sm6350-ipcc