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: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/l2tp/l2tp_core.c

@@ -1227,7 +1227,7 @@ static int l2tp_tunnel_sock_create(u32 tunnel_id, u32 peer_tunnel_id, struct l2t
 	int err = -EINVAL;
 	struct sockaddr_in udp_addr;
 	struct sockaddr_l2tpip ip_addr;
-	struct socket *sock;
+	struct socket *sock = NULL;
 
 	switch (cfg->encap) {
 	case L2TP_ENCAPTYPE_UDP:

net/l2tp/l2tp_core.h

@@ -152,7 +152,7 @@ struct l2tp_tunnel_cfg {
 	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 {