tcp: cdg: use div_u64()

Fixes cross-compile to mips.
Signed-off-by: NKenneth Klette Jonassen <kennetkl@ifi.uio.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_cdg.c

@@ -145,7 +145,7 @@ static void tcp_cdg_hystart_update(struct sock *sk)
 		return;
 
 	if (hystart_detect & HYSTART_ACK_TRAIN) {
-		u32 now_us = local_clock() / NSEC_PER_USEC;
+		u32 now_us = div_u64(local_clock(), NSEC_PER_USEC);
 
 		if (ca->last_ack == 0 || !tcp_is_cwnd_limited(sk)) {
 			ca->last_ack = now_us;