tcp: export do_tcp_sendpages and tcp_rate_check_app_limited functions

Export do_tcp_sendpages and tcp_rate_check_app_limited, since tls will need to
sendpages while the socket is already locked.

tcp_sendpage is exported, but requires the socket lock to not be held already.

Signed-off-by: Aviad Yehezkel <aviadye@mellanox.com>
Signed-off-by: Ilya Lesokhin <ilyal@mellanox.com>
Signed-off-by: Boris Pismenny <borisp@mellanox.com>
Signed-off-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c
index ad99569..3330a37 100644
--- a/net/ipv4/tcp_rate.c
+++ b/net/ipv4/tcp_rate.c
@@ -185,3 +185,4 @@
 		tp->app_limited =
 			(tp->delivered + tcp_packets_in_flight(tp)) ? : 1;
 }
+EXPORT_SYMBOL_GPL(tcp_rate_check_app_limited);