Revert "Zero initial timestamps are valid" changeset.

I am still not sure that this change all by itself is enough
to make us accept zero initial timestamps properly. 

Cset exclude: davem@nuts.ninka.net|ChangeSet|20031025060257|60993

net/ipv4/tcp_ipv4.c

@@ -1465,6 +1465,15 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 		tp.saw_tstamp = 0;
 	}
 
+	if (tp.saw_tstamp && !tp.rcv_tsval) {
+		/* Some OSes (unknown ones, but I see them on web server, which
+		 * contains information interesting only for windows'
+		 * users) do not send their stamp in SYN. It is easy case.
+		 * We simply do not advertise TS support.
+		 */
+		tp.saw_tstamp = 0;
+		tp.tstamp_ok  = 0;
+	}
 	tp.tstamp_ok = tp.saw_tstamp;
 
 	tcp_openreq_init(req, &tp, skb);