[ALSA] Remove nested mutexes in seq_ports.c

Removed nested mutexes in the removal routine of port connections.
The port is guaranteed to be offline before calling it, so no mutex
is needed.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/seq/seq_ports.c

@@ -221,7 +221,6 @@ static void clear_subscriber_list(struct snd_seq_client *client,
 {
 	struct list_head *p, *n;
 
-	down_write(&grp->list_mutex);
 	list_for_each_safe(p, n, &grp->list_head) {
 		struct snd_seq_subscribers *subs;
 		struct snd_seq_client *c;
@@ -259,7 +258,6 @@ static void clear_subscriber_list(struct snd_seq_client *client,
 			snd_seq_client_unlock(c);
 		}
 	}
-	up_write(&grp->list_mutex);
 }
 
 /* delete port data */