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/mpls/mpls_gso.c

@@ -62,6 +62,7 @@ out:
 
 static struct packet_offload mpls_mc_offload __read_mostly = {
 	.type = cpu_to_be16(ETH_P_MPLS_MC),
+	.priority = 15,
 	.callbacks = {
 		.gso_segment    =	mpls_gso_segment,
 	},
@@ -69,6 +70,7 @@ static struct packet_offload mpls_mc_offload __read_mostly = {
 
 static struct packet_offload mpls_uc_offload __read_mostly = {
 	.type = cpu_to_be16(ETH_P_MPLS_UC),
+	.priority = 15,
 	.callbacks = {
 		.gso_segment    =	mpls_gso_segment,
 	},