dt-bindings: display/msm: dpu-msm8998: add missing DPU opp-table

The 'display-controller' child (DPU) of Display SubSystem (MDSS) uses
opp-table, so reference it which allows restricting DPU schema to fixed
list of properties.

Fixes: 6e986a8f ("dt-bindings: display: msm: Add binding for msm8998 dpu")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/497896/
Link: https://lore.kernel.org/r/20220817062059.18640-2-krzysztof.kozlowski@linaro.orgSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

Documentation/devicetree/bindings/display/msm/dpu-msm8998.yaml

@@ -62,6 +62,7 @@ patternProperties:
   "^display-controller@[0-9a-f]+$":
     type: object
     description: Node containing the properties of DPU.
+    additionalProperties: false
 
     properties:
       compatible:
@@ -105,6 +106,9 @@ patternProperties:
         maxItems: 1
 
       operating-points-v2: true
+      opp-table:
+        type: object
+
       ports:
         $ref: /schemas/graph.yaml#/properties/ports
         description: |