net: send RFC1542 compliant value for bootp requests

RFC1542, 3.2:
"The 'secs' field of a BOOTREQUEST message SHOULD represent the
elapsed time, in seconds, since the client sent its first BOOTREQUEST
message.  Note that this implies that the 'secs' field of the first
BOOTREQUEST message SHOULD be set to zero."

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

net/bootp.c

@@ -711,7 +711,11 @@ void bootp_request(void)
 	bp->bp_htype = HWT_ETHER;
 	bp->bp_hlen = HWL_ETHER;
 	bp->bp_hops = 0;
-	bp->bp_secs = htons(get_timer(0) / 1000);
+	/*
+	 * according to RFC1542, should be 0 on first request, secs since
+	 * first request otherwise
+	 */
+	bp->bp_secs = htons(get_timer(bootp_start) / 1000);
 	zero_ip.s_addr = 0;
 	net_write_ip(&bp->bp_ciaddr, zero_ip);
 	net_write_ip(&bp->bp_yiaddr, zero_ip);
@@ -905,7 +909,7 @@ static void dhcp_send_request_packet(struct bootp_hdr *bp_offer)
 	bp->bp_htype = HWT_ETHER;
 	bp->bp_hlen = HWL_ETHER;
 	bp->bp_hops = 0;
-	bp->bp_secs = htons(get_timer(0) / 1000);
+	bp->bp_secs = htons(get_timer(bootp_start) / 1000);
 	/* Do not set the client IP, your IP, or server IP yet, since it
 	 * hasn't been ACK'ed by the server yet */