[ALSA] Fix disconnection of proc interface

- Add the linked list to each proc entry to enable a single-shot
  disconnection (unregister)
- Deprecate snd_info_unregister(), use snd_info_free_entry()
- Removed NULL checks of snd_info_free_entry()

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>
diff --git a/sound/core/info_oss.c b/sound/core/info_oss.c
index bb2c40d..3ebc349 100644
--- a/sound/core/info_oss.c
+++ b/sound/core/info_oss.c
@@ -131,10 +131,8 @@
 
 int snd_info_minor_unregister(void)
 {
-	if (snd_sndstat_proc_entry) {
-		snd_info_unregister(snd_sndstat_proc_entry);
-		snd_sndstat_proc_entry = NULL;
-	}
+	snd_info_free_entry(snd_sndstat_proc_entry);
+	snd_sndstat_proc_entry = NULL;
 	return 0;
 }