x25: Use sock_orphan() instead of open-coded (and buggy) variant.

It doesn't grab the sk_callback_lock, it doesn't NULL out
the sk->sk_sleep waitqueue pointer, etc.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index bcb091f..7b1c6ef 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -612,8 +612,7 @@
 			break;
 	}
 
-	sock->sk	= NULL;
-	sk->sk_socket	= NULL;	/* Not used, but we should do this */
+	sock_orphan(sk);
 out:
 	return 0;
 }