media: dt-bindings: qcom,sm8250-venus: document OPP table

Venus on Qualcomm SM8250 uses Operating Performance Points (both in DTS
and driver):

  sm8250-hdk.dtb: video-codec@aa00000: 'operating-points-v2', 'opp-table' do not match any of the regexes: 'pinctrl-[0-9]+'
Signed-off-by: NKrzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@kernel.org>

Documentation/devicetree/bindings/media/qcom,sm8250-venus.yaml

@@ -51,6 +51,10 @@ properties:
       - const: cpu-cfg
       - const: video-mem
 
+  operating-points-v2: true
+  opp-table:
+    type: object
+
   resets:
     maxItems: 2