neigh: reorder struct neighbour

It is important to move nud_state outside of the often modified cache
line (because of refcnt), to reduce false sharing in neigh_event_send()

This is a followup of commit 0ed8ddf4 (neigh: Protect neigh->ha[]
with a seqlock)

This gives a 7% speedup on routing test with IP route cache disabled.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/neighbour.h

@@ -96,16 +96,16 @@ struct neighbour {
 	struct neigh_parms	*parms;
 	unsigned long		confirmed;
 	unsigned long		updated;
-	__u8			flags;
-	__u8			nud_state;
-	__u8			type;
-	__u8			dead;
+	rwlock_t		lock;
 	atomic_t		refcnt;
 	struct sk_buff_head	arp_queue;
 	struct timer_list	timer;
 	unsigned long		used;
 	atomic_t		probes;
-	rwlock_t		lock;
+	__u8			flags;
+	__u8			nud_state;
+	__u8			type;
+	__u8			dead;
 	seqlock_t		ha_lock;
 	unsigned char		ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))];
 	struct hh_cache		*hh;