vlan: Set correct source MAC address with TX VLAN offload enabled

With TX VLAN offload enabled the source MAC address for frames sent using the
VLAN interface is currently set to the address of the real interface. This is
wrong since the VLAN interface may be configured with a different address.

The bug was introduced in commit 2205369a
("vlan: Fix header ops passthru when doing TX VLAN offload.").

This patch sets the source address before calling the create function of the
real interface.
Signed-off-by: NPeter Boström <peter.bostrom@netrounds.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/8021q/vlan_dev.c

@@ -538,6 +538,9 @@ static int vlan_passthru_hard_header(struct sk_buff *skb, struct net_device *dev
 	struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
 	struct net_device *real_dev = vlan->real_dev;
 
+	if (saddr == NULL)
+		saddr = dev->dev_addr;
+
 	return dev_hard_header(skb, real_dev, type, daddr, saddr, len);
 }