ixgbevf: Fix IPv6 GSO type checks

Based on patch from Sridhar Samudrala

The following patch fixes the check for IPv6 GSO packet in ixgbevf
driver to use skb_is_gso_v6(). SKB_GSO_DODGY is also set
when packets are forwarded from a guest.

CC: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ixgbevf/ixgbevf_main.c

@@ -2781,7 +2781,7 @@ static int ixgbevf_tso(struct ixgbevf_adapter *adapter,
 								 IPPROTO_TCP,
 								 0);
 			adapter->hw_tso_ctxt++;
-		} else if (skb_shinfo(skb)->gso_type == SKB_GSO_TCPV6) {
+		} else if (skb_is_gso_v6(skb)) {
 			ipv6_hdr(skb)->payload_len = 0;
 			tcp_hdr(skb)->check =
 			    ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,