ASoC: audio-graph-scu-card: add missing MIX binding example

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/audio-graph-scu-card.txt

@@ -35,7 +35,7 @@ Required properties:
 - compatible				: "audio-graph-scu-card";
 - dais					: list of CPU DAI port{s}
 
-Example
+Example 1. Sampling Rate Conversion
 
 	sound_card {
 		compatible = "audio-graph-scu-card";
@@ -70,3 +70,48 @@ Example
 			};
 		};
 	};
+
+Example 2. 2 CPU 1 Codec (Mixing)
+
+	sound_card {
+		compatible = "audio-graph-scu-card";
+
+		label = "sound-card";
+		prefix = "codec";
+		routing = "codec Playback", "DAI0 Playback",
+			"codec Playback", "DAI1 Playback";
+		convert-rate = <48000>;
+
+		dais = <&cpu_port0
+			&cpu_port1>;
+	};
+
+	audio-codec {
+		...
+
+		port {
+			codec_endpoint: endpoint {
+				remote-endpoint = <&cpu_endpoint0>;
+			};
+		};
+	};
+
+	dai-controller {
+		...
+		ports {
+			cpu_port0: port {
+				cpu_endpoint0: endpoint {
+					remote-endpoint = <&codec_endpoint>;
+
+					dai-format = "left_j";
+					...
+				};
+			};
+			cpu_port1: port {
+				cpu_endpoint1: endpoint {
+					dai-format = "left_j";
+					...
+				};
+			};
+		};
+	};