netfilter: nf_queue: place volatile data in own cacheline

As the comment indicates, the data at the end of nfqnl_instance struct is
written on every queue/dequeue, so it should reside in its own cacheline.

Before this change, 'lock' was in first cacheline so we dirtied both.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nfnetlink_queue.c

@@ -69,7 +69,7 @@ struct nfqnl_instance {
  * Following fields are dirtied for each queued packet,
  * keep them in same cache line if possible.
  */
-	spinlock_t	lock;
+	spinlock_t	lock	____cacheline_aligned_in_smp;
 	unsigned int	queue_total;
 	unsigned int	id_sequence;		/* 'sequence' of pkt ids */
 	struct list_head queue_list;		/* packets in queue */