gso: Handle Trans-Ether-Bridging protocol in skb_network_protocol()

Rather than having logic to calculate inner protocol in every
tunnel gso handler move it to gso code. This simplifies code.

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Cong Wang <amwang@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 0ae038a..0bf5d39 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2311,7 +2311,6 @@
 	struct sk_buff *segs = ERR_PTR(-EINVAL);
 	int mac_len = skb->mac_len;
 	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
-	struct ethhdr *inner_eth = (struct ethhdr *)skb_inner_mac_header(skb);
 	__be16 protocol = skb->protocol;
 	netdev_features_t enc_features;
 	int outer_hlen;
@@ -2324,8 +2323,7 @@
 	skb_reset_mac_header(skb);
 	skb_set_network_header(skb, skb_inner_network_offset(skb));
 	skb->mac_len = skb_inner_network_offset(skb);
-	inner_eth = (struct ethhdr *)skb_mac_header(skb);
-	skb->protocol = inner_eth->h_proto;
+	skb->protocol = htons(ETH_P_TEB);
 
 	/* segment inner packet. */
 	enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);