dt-bindings: display: msm: sm6350-mdss: document DP controller subnode

Document the displayport controller subnode of the SM6350 MDSS.
Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/585468/
Link: https://lore.kernel.org/r/20240329-sm6350-dp-v2-2-e46dceb32ef5@fairphone.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Documentation/devicetree/bindings/display/msm/qcom,sm6350-mdss.yaml

@@ -53,6 +53,15 @@ patternProperties:
       compatible:
         const: qcom,sm6350-dpu
 
+  "^displayport-controller@[0-9a-f]+$":
+    type: object
+    additionalProperties: true
+
+    properties:
+      compatible:
+        contains:
+          const: qcom,sm6350-dp
+
   "^dsi@[0-9a-f]+$":
     type: object
     additionalProperties: true