[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/hwdep.c b/sound/core/hwdep.c
index 8bd0dcc..cbd8a63 100644
--- a/sound/core/hwdep.c
+++ b/sound/core/hwdep.c
@@ -497,7 +497,7 @@
 
 static void __exit snd_hwdep_proc_done(void)
 {
-	snd_info_unregister(snd_hwdep_proc_entry);
+	snd_info_free_entry(snd_hwdep_proc_entry);
 }
 #else /* !CONFIG_PROC_FS */
 #define snd_hwdep_proc_init()