netlabel: return msg overflow error from netlbl_cipsov4_list faster

Currently, we are trying to place the information from the kernel to
1, 2, 3 and 4 pages sequentially. These pages are allocated via slab.
Though, from the slab point of view steps 3 and 4 are equivalent on
most architectures. So, lets skip 3 pages attempt.

By the way, should we switch from .doit to .dumpit interface here?
The amount of data seems quite big for me.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Acked-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netlabel/netlabel_cipso_v4.c

@@ -591,7 +591,7 @@ static int netlbl_cipsov4_list(struct sk_buff *skb, struct genl_info *info)
 	if (nlsze_mult < 4) {
 		rcu_read_unlock();
 		kfree_skb(ans_skb);
-		nlsze_mult++;
+		nlsze_mult *= 2;
 		goto list_start;
 	}
 list_failure_lock: