[ALSA] Fix ASoC s3c24xx-pcm spinlock bug

This should fix a spinlock lockup bug on the s3c24xx arch.
From: Zoltan Devai <zdevai@gmail.com>

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>