vti4: Don't count header length twice.

commit a3245236 upstream.

We currently count the size of LL_MAX_HEADER and struct iphdr
twice for vti4 devices, this leads to a wrong device mtu.
The size of LL_MAX_HEADER and struct iphdr is already counted in
ip_tunnel_bind_dev(), so don't do it again in vti_tunnel_init().

Fixes: b9959fd3 ("vti: switch to new ip tunnel code")
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>

net/ipv4/ip_vti.c

@@ -582,7 +582,6 @@ static void vti_tunnel_setup(struct net_device *dev)
 	dev->type		= ARPHRD_TUNNEL;
 	dev->destructor		= vti_dev_free;
 
-	dev->hard_header_len	= LL_MAX_HEADER + sizeof(struct iphdr);
 	dev->mtu		= ETH_DATA_LEN;
 	dev->flags		= IFF_NOARP;
 	dev->iflink		= 0;