e1000: FIX: enable hw TSO for IPV6

Enable TSO for IPV6. All e1000 hardware supports it. This reduces CPU
utilizations by 50% when transmitting IPv6 frames.

Fix symbol naming enabling ipv6 TSO. Turn off TSO6 for 10/100.

Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
diff --git a/drivers/net/e1000/e1000_ethtool.c b/drivers/net/e1000/e1000_ethtool.c
index 82d2c78..b9c0927 100644
--- a/drivers/net/e1000/e1000_ethtool.c
+++ b/drivers/net/e1000/e1000_ethtool.c
@@ -348,6 +348,13 @@
 	else
 		netdev->features &= ~NETIF_F_TSO;
 
+#ifdef NETIF_F_TSO6
+	if (data)
+		netdev->features |= NETIF_F_TSO6;
+	else
+		netdev->features &= ~NETIF_F_TSO6;
+#endif
+
 	DPRINTK(PROBE, INFO, "TSO is %s\n", data ? "Enabled" : "Disabled");
 	adapter->tso_force = TRUE;
 	return 0;