ASoC: Remove unused cache_only from struct snd_soc_codec

There are no real users for cache_only in "struct snd_soc_codec" so remove
it and needless debugfs node.
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

include/sound/soc.h

@@ -792,7 +792,6 @@ struct snd_soc_codec {
 	unsigned int ac97_registered:1; /* Codec has been AC97 registered */
 	unsigned int ac97_created:1; /* Codec has been created by SoC */
 	unsigned int cache_init:1; /* codec cache has been initialized */
-	u32 cache_only;  /* Suppress writes to hardware */
 	u32 cache_sync; /* Cache needs to be synced to hardware */
 
 	/* codec IO */

sound/soc/soc-core.c

@@ -311,8 +311,6 @@ static void soc_init_codec_debugfs(struct snd_soc_component *component)
 
 	debugfs_create_bool("cache_sync", 0444, codec->component.debugfs_root,
 			    &codec->cache_sync);
-	debugfs_create_bool("cache_only", 0444, codec->component.debugfs_root,
-			    &codec->cache_only);
 
 	codec->debugfs_reg = debugfs_create_file("codec_reg", 0644,
 						 codec->component.debugfs_root,