net: Add GSO to vlan_features initialization

Just add GSO to vlan_features initialization, and update comments.

When we set offload features, vlan_dev_fix_features() will do more check.
In vlan_dev_fix_features(), final features is decided by
features of real device and vlan_features of real device.
Signed-off-by: NShan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -5488,11 +5488,12 @@ int register_netdevice(struct net_device *dev)
 		dev->features |= NETIF_F_NOCACHE_COPY;
 	}
 
-	/* Enable GRO and NETIF_F_HIGHDMA for vlans by default,
-	 * vlan_dev_init() will do the dev->features check, so these features
-	 * are enabled only if supported by underlying device.
+	/* Enable GSO, GRO and NETIF_F_HIGHDMA for vlans by default,
+	 * vlan_dev_fix_features() will do the features check,
+	 * so NETIF_F_HIGHDMA feature is enabled only if supported
+	 * by underlying device.
 	 */
-	dev->vlan_features |= (NETIF_F_GRO | NETIF_F_HIGHDMA);
+	dev->vlan_features |= (NETIF_F_SOFT_FEATURES | NETIF_F_HIGHDMA);
 
 	ret = call_netdevice_notifiers(NETDEV_POST_INIT, dev);
 	ret = notifier_to_errno(ret);