ASoC: dt-bindings: fsl,micfil: Document #sound-dai-cells

imx8mp.dtsi passes #sound-dai-cells = <0> in the micfil node.

Document #sound-dai-cells to fix the following schema warning:

audio-controller@30ca0000: '#sound-dai-cells' does not match any of the regexes: 'pinctrl-[0-9]+'
from schema $id: http://devicetree.org/schemas/sound/fsl,micfil.yaml#

Signed-off-by: Fabio Estevam <[email protected]>
Reviewed-by: Adam Ford <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: Fabio Estevam

Documentation/devicetree/bindings/sound/fsl,micfil.yaml

@@ -56,6 +56,9 @@ properties:
       - const: clkext3
     minItems: 2
 
+  "#sound-dai-cells":
+    const: 0
+
 required:
   - compatible
   - reg