ip6_vti: simplify stats handling in vti6_xmit

Same as ip_vti, use iptunnel_xmit_stats to updates stats in tunnel xmit
code path.
Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6_vti.c

@@ -503,17 +503,9 @@ vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl)
 	skb->dev = skb_dst(skb)->dev;
 
 	err = dst_output(t->net, skb->sk, skb);
-	if (net_xmit_eval(err) == 0) {
-		struct pcpu_sw_netstats *tstats = this_cpu_ptr(dev->tstats);
-
-		u64_stats_update_begin(&tstats->syncp);
-		tstats->tx_bytes += pkt_len;
-		tstats->tx_packets++;
-		u64_stats_update_end(&tstats->syncp);
-	} else {
-		stats->tx_errors++;
-		stats->tx_aborted_errors++;
-	}
+	if (net_xmit_eval(err) == 0)
+		err = pkt_len;
+	iptunnel_xmit_stats(dev, err);
 
 	return 0;
 tx_err_link_failure: