ALSA: core: init: use DECLARE_COMPLETION_ONSTACK() macro

Follow recommendation in Documentation/scheduler/completion.rst and use
macro to declare local 'struct completion'
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200902212133.30964-9-pierre-louis.bossart@linux.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/init.c

@@ -519,10 +519,9 @@ EXPORT_SYMBOL(snd_card_free_when_closed);
  */
 int snd_card_free(struct snd_card *card)
 {
-	struct completion released;
+	DECLARE_COMPLETION_ONSTACK(released);
 	int ret;
 
-	init_completion(&released);
 	card->release_completion = &released;
 	ret = snd_card_free_when_closed(card);
 	if (ret)