ASoC: Remove unused 'list' field form card

The global card list was removed in commit b19e6e7b ("ASoC: core: Use driver
core probe deferral"). The 'list' field of the snd_soc_card struct has been
unused since then. This patch removes the field.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

include/sound/soc.h

@@ -958,7 +958,6 @@ struct snd_soc_card {
 	struct snd_card *snd_card;
 	struct module *owner;
 
-	struct list_head list;
 	struct mutex mutex;
 	struct mutex dapm_mutex;
 

sound/soc/soc-core.c

@@ -3745,7 +3745,6 @@ int snd_soc_register_card(struct snd_soc_card *card)
 	for (i = 0; i < card->num_links; i++)
 		card->rtd[i].dai_link = &card->dai_link[i];
 
-	INIT_LIST_HEAD(&card->list);
 	INIT_LIST_HEAD(&card->dapm_dirty);
 	card->instantiated = 0;
 	mutex_init(&card->mutex);