ASoC: io: Remove hw_read() operation

We now no longer have any users of hw_read() in the kernel so remove the
code in order to prevent any new users being added. Users should be using
regmap.
Signed-off-by: Mark Brown <broonie@linaro.org>

include/sound/soc.h

@@ -695,7 +695,6 @@ struct snd_soc_codec {
 	/* codec IO */
 	void *control_data; /* codec control (i2c/3wire) data */
 	hw_write_t hw_write;
-	unsigned int (*hw_read)(struct snd_soc_codec *, unsigned int);
 	unsigned int (*read)(struct snd_soc_codec *, unsigned int);
 	int (*write)(struct snd_soc_codec *, unsigned int, unsigned int);
 	void *reg_cache;