tcp: fix get_timewait4_sock() delay computation on 64bit

It seems I missed one change in get_timewait4_sock() to compute
the remaining time before deletion of IPV4 timewait socket.

This could result in wrong output in /proc/net/tcp for tm->when field.

Fixes: 96f817fede ("tcp: shrink tcp6_timewait_sock by one cache line")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_ipv4.c

@@ -2628,7 +2628,7 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
 {
 	__be32 dest, src;
 	__u16 destp, srcp;
-	long delta = tw->tw_ttd - jiffies;
+	s32 delta = tw->tw_ttd - inet_tw_time_stamp();
 
 	dest  = tw->tw_daddr;
 	src   = tw->tw_rcv_saddr;