ASoC: Add control_type in snd_soc_codec

This is mainly used by the soc-cache code to easily determine the
currently used underlying serial bus.  Set SND_SOC_CUSTOM to 1 so we
can distinguish it if it is not initialized or set.
Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

include/sound/soc.h

@@ -248,7 +248,7 @@ typedef int (*hw_write_t)(void *,const char* ,int);
 extern struct snd_ac97_bus_ops soc_ac97_ops;
 
 enum snd_soc_control_type {
-	SND_SOC_CUSTOM,
+	SND_SOC_CUSTOM = 1,
 	SND_SOC_I2C,
 	SND_SOC_SPI,
 };
@@ -539,6 +539,7 @@ struct snd_soc_codec {
 
 	/* codec IO */
 	void *control_data; /* codec control (i2c/3wire) data */
+	enum snd_soc_control_type control_type;
 	hw_write_t hw_write;
 	unsigned int (*hw_read)(struct snd_soc_codec *, unsigned int);
 	unsigned int (*read)(struct snd_soc_codec *, unsigned int);