ARM: dts: rockchip: Add SPDIF optical out on Radxa Rock2 Square

Enable the SPDIF optical output on Radxa Rock2 square boards
Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm/boot/dts/rk3288-rock2-square.dts

@@ -49,6 +49,20 @@ chosen {
 		stdout-path = "serial2:115200n8";
 	};
 
+	sound {
+		compatible = "simple-audio-card";
+		simple-audio-card,name = "SPDIF";
+		simple-audio-card,dai-link@1 {  /* S/PDIF - S/PDIF */
+			cpu { sound-dai = <&spdif>; };
+			codec { sound-dai = <&spdif_out>; };
+		};
+	};
+
+	spdif_out: spdif-out {
+		compatible = "linux,spdif-dit";
+		#sound-dai-cells = <0>;
+	};
+
 	vcc_usb_host: vcc-host-regulator {
 		compatible = "regulator-fixed";
 		enable-active-high;
@@ -136,6 +150,10 @@ sdmmc_pwr: sdmmc-pwr {
 	};
 };
 
+&spdif {
+	status = "okay";
+};
+
 &uart2 {
 	status = "okay";
 };