[NET]: Move hardware header operations out of netdevice.

Since hardware header operations are part of the protocol class
not the device instance, make them into a separate object and
save memory.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index ca8090f..1a1740a 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -343,8 +343,8 @@
  *  physical devices.
  */
 int vlan_dev_hard_header(struct sk_buff *skb, struct net_device *dev,
-			 unsigned short type, void *daddr, void *saddr,
-			 unsigned len)
+			 unsigned short type,
+			 const void *daddr, const void *saddr, unsigned len)
 {
 	struct vlan_hdr *vhdr;
 	unsigned short veth_TCI = 0;