[NET]: Store skb->timestamp as offset to a base timestamp

Reduces skb size by 8 bytes on 64-bit.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/econet/af_econet.c b/net/econet/af_econet.c
index 8f06399..4a62093 100644
--- a/net/econet/af_econet.c
+++ b/net/econet/af_econet.c
@@ -159,7 +159,7 @@
 	err = memcpy_toiovec(msg->msg_iov, skb->data, copied);
 	if (err)
 		goto out_free;
-	sk->sk_stamp = skb->stamp;
+	skb_get_timestamp(skb, &sk->sk_stamp);
 
 	if (msg->msg_name)
 		memcpy(msg->msg_name, skb->cb, msg->msg_namelen);