tcp: ipv4: initialize unicast_sock sk_pacing_rate

When I added sk_pacing_rate field, I forgot to initialize its value
in the per cpu unicast_sock used in ip_send_unicast_reply()

This means that for sch_fq users, RST packets, or ACK packets sent
on behalf of TIME_WAIT sockets might be sent to slowly or even dropped
once we reach the per flow limit.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Fixes: 95bd09eb ("tcp: TSO packets automatic sizing")
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/ip_output.c

@@ -1517,6 +1517,7 @@ static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = {
 		.sk_wmem_alloc	= ATOMIC_INIT(1),
 		.sk_allocation	= GFP_ATOMIC,
 		.sk_flags	= (1UL << SOCK_USE_WRITE_QUEUE),
+		.sk_pacing_rate = ~0U,
 	},
 	.pmtudisc	= IP_PMTUDISC_WANT,
 	.uc_ttl		= -1,