net: vlan: enable soft features regardless of underlying device

If gso/gro feature of underlying device is turned off，
then new created vlan device never can turn gso/gro on. 

Although underlying device don't support TSO, we still
should use software segments for vlan device.

Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/8021q/vlan_dev.c

@@ -586,9 +586,14 @@ static void vlan_dev_uninit(struct net_device *dev)
 static u32 vlan_dev_fix_features(struct net_device *dev, u32 features)
 {
 	struct net_device *real_dev = vlan_dev_info(dev)->real_dev;
+	u32 old_features = features;
 
 	features &= real_dev->features;
 	features &= real_dev->vlan_features;
+
+	if (old_features & NETIF_F_SOFT_FEATURES)
+		features |= old_features & NETIF_F_SOFT_FEATURES;
+
 	if (dev_ethtool_get_rx_csum(real_dev))
 		features |= NETIF_F_RXCSUM;
 	features |= NETIF_F_LLTX;