flow_keys: Record IP layer protocol in skb_flow_dissect()

skb_flow_dissect() dissects only transport header type in ip_proto. It dose not
give any information about IPv4 or IPv6.

This patch adds new member, n_proto, to struct flow_keys. Which records the
IP layer type. i.e IPv4 or IPv6.

This can be used in netdev->ndo_rx_flow_steer driver function to dissect flow.

Adding new member to flow_keys increases the struct size by around 4 bytes.
This causes BUILD_BUG_ON(sizeof(qcb->data) < sz); to fail in
qdisc_cb_private_validate()

So increase data size by 4

Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 107ed12..c2b53c1 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -175,6 +175,7 @@
 		break;
 	}
 
+	flow->n_proto = proto;
 	flow->ip_proto = ip_proto;
 	flow->ports = skb_flow_get_ports(skb, nhoff, ip_proto);
 	flow->thoff = (u16) nhoff;