[NETFILTER]: nfnetlink_log: fix use after free

Paranoia: instance_put() might have freed the inst pointer when we
spin_unlock_bh().

Signed-off-by: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/nfnetlink_log.c

@@ -393,8 +393,8 @@ static void nfulnl_timer(unsigned long data)
 
 	spin_lock_bh(&inst->lock);
 	__nfulnl_send(inst);
-	instance_put(inst);
 	spin_unlock_bh(&inst->lock);
+	instance_put(inst);
 }
 
 /* This is an inline function, we don't really care about a long