[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/oss/mixer_oss.c b/sound/core/oss/mixer_oss.c
index 75a9505..00c95de 100644
--- a/sound/core/oss/mixer_oss.c
+++ b/sound/core/oss/mixer_oss.c
@@ -1193,10 +1193,8 @@
 
 static void snd_mixer_oss_proc_done(struct snd_mixer_oss *mixer)
 {
-	if (mixer->proc_entry) {
-		snd_info_unregister(mixer->proc_entry);
-		mixer->proc_entry = NULL;
-	}
+	snd_info_free_entry(mixer->proc_entry);
+	mixer->proc_entry = NULL;
 }
 #else /* !CONFIG_PROC_FS */
 #define snd_mixer_oss_proc_init(mix)