ARM: mvebu: enable S/PDIF audio in Armada 370 DB Device Tree

In addition to the analog audio input and output, the Armada 370 DB
also has S/PDIF input and output optical connectors. This commit
improves the Device Tree description of the Armada 370 DB platform to
enable the S/PDIF support.
Signed-off-by: NThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/armada-370-db.dts

@@ -163,7 +163,15 @@
 	sound {
 	      compatible = "marvell,a370db-audio";
 	      marvell,audio-controller = <&audio_controller>;
-	      marvell,audio-codec = <&audio_codec>;
+	      marvell,audio-codec = <&audio_codec &spdif_out &spdif_in>;
 	      status = "okay";
 	};
+
+	spdif_out: spdif-out {
+	      compatible = "linux,spdif-dit";
+	};
+
+	spdif_in: spdif-in {
+	      compatible = "linux,spdif-dir";
+	};
 };