ipv6: remove aca_lock spinlock from struct ifacaddr6

no user uses this lock.
Signed-off-by: NLi RongQing <roy.qing.li@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/if_inet6.h

@@ -146,7 +146,6 @@ struct ifacaddr6 {
 	struct ifacaddr6	*aca_next;
 	int			aca_users;
 	atomic_t		aca_refcnt;
-	spinlock_t		aca_lock;
 	unsigned long		aca_cstamp;
 	unsigned long		aca_tstamp;
 };

net/ipv6/anycast.c

@@ -235,7 +235,6 @@ static struct ifacaddr6 *aca_alloc(struct rt6_info *rt,
 	/* aca_tstamp should be updated upon changes */
 	aca->aca_cstamp = aca->aca_tstamp = jiffies;
 	atomic_set(&aca->aca_refcnt, 1);
-	spin_lock_init(&aca->aca_lock);
 
 	return aca;
 }