ASoC: Convert MT8183 DA7219 sound card to DT schema

Convert the Device Tree binding for MT8183-based boards using the
DA7219 headset codec and optional MAX98357, RT1015 or RT1015P speaker
amplifiers from the legacy .txt format to DT schema.

This improves binding validation and removes DT schema warnings
for boards using these audio components.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Julien Massot <julien.massot@collabora.com>
Link: https://patch.msgid.link/20250826-mtk-dtb-warnings-v3-5-20e89886a20e@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Julien Massot

Documentation/devicetree/bindings/sound/mediatek,mt8183_da7219.yaml

@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/mediatek,mt8183_da7219.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MediaTek MT8183 sound card with external codecs
+
+maintainers:
+  - Julien Massot <jmassot@collabora.com>
+
+description:
+  MediaTek MT8183 SoC-based sound cards with DA7219 as headset codec,
+  and MAX98357A, RT1015 or RT1015P as speaker amplifiers. Optionally includes HDMI codec.
+
+properties:
+  compatible:
+    enum:
+      - mediatek,mt8183_da7219_max98357
+      - mediatek,mt8183_da7219_rt1015
+      - mediatek,mt8183_da7219_rt1015p
+
+  mediatek,headset-codec:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: Phandle to the DA7219 headset codec.
+
+  mediatek,platform:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: Phandle to the MT8183 ASoC platform (e.g., AFE node).
+
+  mediatek,hdmi-codec:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: Optional phandle to the HDMI codec (e.g., IT6505).
+
+required:
+  - compatible
+  - mediatek,headset-codec
+  - mediatek,platform
+
+additionalProperties: false
+
+examples:
+  - |
+    sound {
+        compatible = "mediatek,mt8183_da7219_max98357";
+        mediatek,headset-codec = <&da7219>;
+        mediatek,hdmi-codec = <&it6505dptx>;
+        mediatek,platform = <&afe>;
+    };