net: vxlan: use kfree_skb_reason() in vxlan_mdb_xmit()

Replace kfree_skb() with kfree_skb_reason() in vxlan_mdb_xmit. No drop
reasons are introduced in this commit.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan/vxlan_mdb.c

@@ -1712,7 +1712,7 @@ netdev_tx_t vxlan_mdb_xmit(struct vxlan_dev *vxlan,
 		vxlan_xmit_one(skb, vxlan->dev, src_vni,
 			       rcu_dereference(fremote->rd), false);
 	else
-		kfree_skb(skb);
+		kfree_skb_reason(skb, SKB_DROP_REASON_VXLAN_NO_REMOTE);
 
 	return NETDEV_TX_OK;
 }