ASoC: dt-bindings: max98520: add initial bindings

add initial bindings for max98520 audio amplifier
Signed-off-by: George Song <george.song@maximintegrated.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211027001431.363-1-george.song@maximintegrated.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/maxim,max98520.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/maxim,max98520.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim Integrated MAX98520 Speaker Amplifier Driver
+
+maintainers:
+  - George Song <george.song@maximintegrated.com>
+
+properties:
+  compatible:
+    const: maxim,max98520
+
+  reg:
+    maxItems: 1
+    description: I2C address of the device.
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      max98520: amplifier@38 {
+        compatible = "maxim,max98520";
+        reg = <0x38>;
+      };
+    };
+