ASoC: dt-bindings: dai-common: Narrow possible sound-dai-cells

Instead of accepting any value for sound-dai-cells, the common DAI
properties schema should narrow them to sane choice.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

---

Mostly sound-dai-cells are 0 or 1, but
Documentation/devicetree/bindings/sound/amlogic,aiu.yaml has value of 2.

Documentation/devicetree/bindings/sound/dai-common.yaml

@@ -13,6 +13,7 @@ allOf:
   - $ref: component-common.yaml#
 
 properties:
-  '#sound-dai-cells': true
+  '#sound-dai-cells':
+    enum: [0, 1, 2]
 
 additionalProperties: true