ipv4: be friend with drop monitor

Replace some dev_kfree_skb() with kfree_skb() calls when
we drop one skb, this might help bug tracking.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 432c28a..83ede2e 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -716,7 +716,7 @@
 
 	if (skb_cow_head(skb, dev->needed_headroom)) {
 		dev->stats.tx_dropped++;
-		dev_kfree_skb(skb);
+		kfree_skb(skb);
 		return;
 	}
 
@@ -732,7 +732,7 @@
 #endif
 tx_error:
 	dev->stats.tx_errors++;
-	dev_kfree_skb(skb);
+	kfree_skb(skb);
 }
 EXPORT_SYMBOL_GPL(ip_tunnel_xmit);