openvswitch: use hard_header_len instead of hardcoded ETH_HLEN

On tx, use hard_header_len while deciding whether to refragment or drop the
packet. That way, all combinations are calculated correctly:

* L2 packet going to L2 interface (the L2 header len is subtracted),
* L2 packet going to L3 interface (the L2 header is included in the packet
  lenght),
* L3 packet going to L3 interface.

Signed-off-by: Jiri Benc <jbenc@redhat.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 1105c4e..49af167 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -791,7 +791,8 @@
 				pskb_trim(skb, ETH_HLEN);
 		}
 
-		if (likely(!mru || (skb->len <= mru + ETH_HLEN))) {
+		if (likely(!mru ||
+		           (skb->len <= mru + vport->dev->hard_header_len))) {
 			ovs_vport_send(vport, skb);
 		} else if (mru <= vport->dev->mtu) {
 			struct net *net = read_pnet(&dp->net);