ipv6 ip6_tunnel: eliminate unused recursion field from ip6_tnl{}.

Commit a43912ab... ("tunnel: eliminate recursion field") eliminated
use of recursion field from tunnel structures, but its definition
still exists in ip6_tnl{}.

Let's remove that unused field.
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip6_tunnel.h

@@ -15,7 +15,6 @@
 struct ip6_tnl {
 	struct ip6_tnl *next;	/* next tunnel in list */
 	struct net_device *dev;	/* virtual device associated with tunnel */
-	int recursion;		/* depth of hard_start_xmit recursion */
 	struct ip6_tnl_parm parms;	/* tunnel configuration parameters */
 	struct flowi fl;	/* flowi template for xmit */
 	struct dst_entry *dst_cache;    /* cached dst */