l2tp: unmanaged L2TPv3 tunnels fixes

Followup to commit 789a4a2c 
(l2tp: Add support for static unmanaged L2TPv3 tunnels)

One missing init in l2tp_tunnel_sock_create() could access random kernel
memory, and a bit field should be unsigned.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 91b1b9c..f0f318e 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -152,7 +152,7 @@
 	struct in_addr		peer_ip;
 	u16			local_udp_port;
 	u16			peer_udp_port;
-	int			use_udp_checksums:1;
+	unsigned int		use_udp_checksums:1;
 };
 
 struct l2tp_tunnel {