dt-bindings: display/msm: qcom, sc8280xp-mdss: add DP / eDP child nodes

Describe DP and eDP devices as subdevices to the MDSS on SC8280XP
platform.

Fixes: 45af56bf ("dt-bindings: display/msm: Add binding for SC8280XP MDSS")
Signed-off-by: NDmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: NRob Herring <robh@kernel.org>
Patchwork: https://patchwork.freedesktop.org/patch/518799/
Link: https://lore.kernel.org/r/20230118031718.1714861-2-dmitry.baryshkov@linaro.orgSigned-off-by: NDmitry Baryshkov <dmitry.baryshkov@linaro.org>

Documentation/devicetree/bindings/display/msm/qcom,sc8280xp-mdss.yaml

@@ -38,6 +38,14 @@ patternProperties:
       compatible:
         const: qcom,sc8280xp-dpu
 
+  "^displayport-controller@[0-9a-f]+$":
+    type: object
+    properties:
+      compatible:
+        enum:
+          - qcom,sc8280xp-dp
+          - qcom,sc8280xp-edp
+
 unevaluatedProperties: false
 
 examples: