l2tp: Fix the connect status check in pppol2tp_getname

The sk->sk_state is bits flag, so need use bit operation check
instead of value check.
Signed-off-by: NGao Feng <fgao@ikuai8.com>
Tested-by: NGuillaume Nault <g.nault@alphalink.fr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/l2tp/l2tp_ppp.c

@@ -856,7 +856,7 @@ static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,
 	error = -ENOTCONN;
 	if (sk == NULL)
 		goto end;
-	if (sk->sk_state != PPPOX_CONNECTED)
+	if (!(sk->sk_state & PPPOX_CONNECTED))
 		goto end;
 
 	error = -EBADF;