net: ipv6: remove 'next' member from inet6_dev

The next pointer within the inet6_dev structure seems not to be used
anywhere. So just remove it. Tested with allmodconfig on x86_64.
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/if_inet6.h

@@ -193,7 +193,6 @@ struct inet6_dev {
 	struct in6_addr		token;
 
 	struct neigh_parms	*nd_parms;
-	struct inet6_dev	*next;
 	struct ipv6_devconf	cnf;
 	struct ipv6_devstat	stats;
 	unsigned long		tstamp; /* ipv6InterfaceTable update timestamp */