[BLUETOOTH] lockdep: annotate sk_lock nesting in AF_BLUETOOTH

=============================================
[ INFO: possible recursive locking detected ]
2.6.18-1.2726.fc6 #1
diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index bbf78e6..29a8fa4 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -770,7 +770,7 @@
 	long timeo;
 	int err = 0;
 
-	lock_sock(sk);
+	lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
 
 	if (sk->sk_state != BT_LISTEN) {
 		err = -EBADFD;
@@ -792,7 +792,7 @@
 
 		release_sock(sk);
 		timeo = schedule_timeout(timeo);
-		lock_sock(sk);
+		lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
 
 		if (sk->sk_state != BT_LISTEN) {
 			err = -EBADFD;