[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/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 77f67b7..699f067 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -169,7 +169,7 @@
 		IP_INC_STATS(IPSTATS_MIB_OUTBCASTPKTS);
 
 	/* Be paranoid, rather than too clever. */
-	if (unlikely(skb_headroom(skb) < hh_len && dev->hard_header)) {
+	if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
 		struct sk_buff *skb2;
 
 		skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));