ASoC: add Audio Graph Card2 Yaml Document

This patch adds Audio Graph Card2 Yaml Document to Linux.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87wnmilu43.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/audio-graph-card2.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/audio-graph-card2.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Audio Graph Card2 Device Tree Bindings
+
+maintainers:
+  - Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
+
+properties:
+  compatible:
+    enum:
+      - audio-graph-card2
+  links:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+  label:
+    maxItems: 1
+  routing:
+    description: |
+      A list of the connections between audio components.
+      Each entry is a pair of strings, the first being the
+      connection's sink, the second being the connection's source.
+    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+  multi:
+    description: Multi-CPU/Codec node
+  dpcm:
+    description: DPCM node
+  codec2codec:
+    description: Codec to Codec node
+
+required:
+  - compatible
+  - links
+
+additionalProperties: false
+
+examples:
+  - |
+    sound {
+        compatible = "audio-graph-card2";
+
+        links = <&cpu_port>;
+    };
+
+    cpu {
+        compatible = "cpu-driver";
+
+        cpu_port: port { cpu_ep: endpoint { remote-endpoint = <&codec_ep>; }; };
+    };
+
+    codec {
+        compatible = "codec-driver";
+
+        port { codec_ep: endpoint { remote-endpoint = <&cpu_ep>; }; };
+    };