ASoC: dt-bindings: Convert dmic-codec to DT schema

Convert the dmic-codec binding to DT schema format.

The '#sound-dai-cells' and 'sound-name-prefix' properties were not
documented, but are in use, so add them.
Reviewed-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20221021175721.4005601-1-robh@kernel.orgSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/dmic-codec.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/dmic-codec.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic PDM Digital microphone (DMIC) codec
+
+maintainers:
+  - Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
+
+allOf:
+  - $ref: name-prefix.yaml#
+
+properties:
+  compatible:
+    const: dmic-codec
+
+  '#sound-dai-cells':
+    const: 0
+
+  dmicen-gpios:
+    description: GPIO specifier for DMIC to control start and stop
+    maxItems: 1
+
+  num-channels:
+    description: Number of microphones on this DAI
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+    maximum: 8
+    default: 8
+
+  modeswitch-delay-ms:
+    description: Delay (in ms) to complete DMIC mode switch
+
+  wakeup-delay-ms:
+    description: Delay (in ms) after enabling the DMIC
+
+required:
+  - compatible
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    dmic {
+        compatible = "dmic-codec";
+        dmicen-gpios = <&gpio4 3 GPIO_ACTIVE_HIGH>;
+        num-channels = <1>;
+        wakeup-delay-ms = <50>;
+        modeswitch-delay-ms = <35>;
+    };
+...

Documentation/devicetree/bindings/sound/dmic.txt

-Device-Tree bindings for Digital microphone (DMIC) codec
-
-This device support generic PDM digital microphone.
-
-Required properties:
-	- compatible: should be "dmic-codec".
-
-Optional properties:
-	- dmicen-gpios: GPIO specifier for dmic to control start and stop
-	- num-channels: Number of microphones on this DAI
-	- wakeup-delay-ms: Delay (in ms) after enabling the DMIC
-	- modeswitch-delay-ms: Delay (in ms) to complete DMIC mode switch
-
-Example node:
-
-	dmic_codec: dmic@0 {
-		compatible = "dmic-codec";
-		dmicen-gpios = <&gpio4 3 GPIO_ACTIVE_HIGH>;
-		num-channels = <1>;
-		wakeup-delay-ms <50>;
-		modeswitch-delay-ms <35>;
-	};