[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/drivers/net/hamradio/yam.c b/drivers/net/hamradio/yam.c
index 401724d..1c94286 100644
--- a/drivers/net/hamradio/yam.c
+++ b/drivers/net/hamradio/yam.c
@@ -1097,8 +1097,7 @@
 
 	skb_queue_head_init(&yp->send_queue);
 
-	dev->hard_header = ax25_hard_header;
-	dev->rebuild_header = ax25_rebuild_header;
+	dev->header_ops = &ax25_header_ops;
 
 	dev->set_mac_address = yam_set_mac_address;