ASoC: dt-bindings: qcom,lpass-cpu: Document required-opps

SC7280 LPASS CPU device node comes with required-opps:

  sc7280-herobrine-crd.dtb: audio@3987000: Unevaluated properties are not allowed ('required-opps' was unexpected)
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20221227163135.102559-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/qcom,lpass-cpu.yaml

@@ -65,6 +65,9 @@ properties:
   power-domain-names:
     maxItems: 1
 
+  required-opps:
+    maxItems: 1
+
   '#sound-dai-cells':
     const: 1