dt-bindings: mailbox: qcom-ipcc: add missing compatible for SM8450

Fill missing compatible already used in SM8450 DTS.
Signed-off-by: David Heidelberg <david@ixit.cz>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220426101837.16201-1-david@ixit.cz

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

@@ -27,6 +27,7 @@ properties:
           - qcom,sm6350-ipcc
           - qcom,sm8250-ipcc
           - qcom,sm8350-ipcc
+          - qcom,sm8450-ipcc
           - qcom,sc7280-ipcc
       - const: qcom,ipcc