ASoC: spdif_transmitter: Add DT support.

Add devicetree support for this dummy audio soc driver.
Signed-off-by: Michal Bachraty <michal.bachraty@streamunlimited.com>
Signed-off-by: Marek Belisko <marek.belisko@streamunlimited.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Documentation/devicetree/bindings/sound/spdif-transmitter.txt

+Device-Tree bindings for dummy spdif transmitter
+
+Required properties:
+	- compatible: should be "linux,spdif-dit".
+
+Example node:
+
+	codec: spdif-transmitter {
+		compatible = "linux,spdif-dit";
+	};

sound/soc/codecs/spdif_transmitter.c

@@ -20,6 +20,7 @@
 #include <sound/soc.h>
 #include <sound/pcm.h>
 #include <sound/initval.h>
+#include <linux/of.h>
 
 #define DRV_NAME "spdif-dit"
 
@@ -52,12 +53,21 @@ static int spdif_dit_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_OF
+static const struct of_device_id spdif_dit_dt_ids[] = {
+	{ .compatible = "linux,spdif-dit", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, spdif_dit_dt_ids);
+#endif
+
 static struct platform_driver spdif_dit_driver = {
 	.probe		= spdif_dit_probe,
 	.remove		= spdif_dit_remove,
 	.driver		= {
 		.name	= DRV_NAME,
 		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(spdif_dit_dt_ids),
 	},
 };