pptp: Accept packet with seq zero

Initialize the PPTP "seq received" value to 0xffffffff, so we don't
ignore packets with seq zero.
Signed-off-by: NBradley Peterson <despite@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ppp/pptp.c

@@ -585,8 +585,8 @@ static int pptp_create(struct net *net, struct socket *sock)
 	po = pppox_sk(sk);
 	opt = &po->proto.pptp;
 
-	opt->seq_sent = 0; opt->seq_recv = 0;
-	opt->ack_recv = 0; opt->ack_sent = 0;
+	opt->seq_sent = 0; opt->seq_recv = 0xffffffff;
+	opt->ack_recv = 0; opt->ack_sent = 0xffffffff;
 
 	error = 0;
 out: