tcp: switch internal pacing timer to CLOCK_TAI

Next patch will use tcp_wstamp_ns to feed internal
TCP pacing timer, so switch to CLOCK_TAI to share same base.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_output.c

@@ -1007,7 +1007,7 @@ static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb)
 	len_ns = (u64)skb->len * NSEC_PER_SEC;
 	do_div(len_ns, rate);
 	hrtimer_start(&tcp_sk(sk)->pacing_timer,
-		      ktime_add_ns(ktime_get(), len_ns),
+		      ktime_add_ns(ktime_get_tai_ns(), len_ns),
 		      HRTIMER_MODE_ABS_PINNED_SOFT);
 	sock_hold(sk);
 }

net/ipv4/tcp_timer.c

@@ -758,7 +758,7 @@ void tcp_init_xmit_timers(struct sock *sk)
 {
 	inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer,
 				  &tcp_keepalive_timer);
-	hrtimer_init(&tcp_sk(sk)->pacing_timer, CLOCK_MONOTONIC,
+	hrtimer_init(&tcp_sk(sk)->pacing_timer, CLOCK_TAI,
 		     HRTIMER_MODE_ABS_PINNED_SOFT);
 	tcp_sk(sk)->pacing_timer.function = tcp_pace_kick;