ALSA: pcm_core: Fix wake_up() optimization

This change fixes the "ALSA: pcm_lib - optimize wake_up() calls for PCM I/O"
commit. New sleeping queue is introduced to separate user space and kernel
space wake_ups. runtime->nowake is renamed to twake (transfer wake).

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index df57a0e..0d428d0 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -894,6 +894,7 @@
 	memset((void*)runtime->control, 0, size);
 
 	init_waitqueue_head(&runtime->sleep);
+	init_waitqueue_head(&runtime->tsleep);
 
 	runtime->status->state = SNDRV_PCM_STATE_OPEN;