net: Add priority to packet_offload objects.

When we scan a packet for GRO processing, we want to see the most
common packet types in the front of the offload_base list.

So add a priority field so we can handle this properly.

IPv4/IPv6 get the highest priority with the implicit zero priority
field.

Next comes ethernet with a priority of 10, and then we have the MPLS
types with a priority of 15.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Suggested-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ethernet/eth.c

@@ -470,6 +470,7 @@ EXPORT_SYMBOL(eth_gro_complete);
 
 static struct packet_offload eth_packet_offload __read_mostly = {
 	.type = cpu_to_be16(ETH_P_TEB),
+	.priority = 10,
 	.callbacks = {
 		.gro_receive = eth_gro_receive,
 		.gro_complete = eth_gro_complete,