dt-bindings: display: msm: dp-controller: document SM8550 compatible

The SM8550 & SM8350 SoC shares the same DP TX IP version, use the
SM8350 compatible as fallback for SM8550.
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/540552/
Link: https://lore.kernel.org/r/20230601-topic-sm8550-upstream-dp-v2-1-e8778109c757@linaro.orgSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Documentation/devicetree/bindings/display/msm/dp-controller.yaml

@@ -29,6 +29,7 @@ properties:
       - items:
           - enum:
               - qcom,sm8450-dp
+              - qcom,sm8550-dp
           - const: qcom,sm8350-dp
 
   reg: