net/rds: correct socket tunable error in rds_tcp_tune()

Correct an error where setting /proc/sys/net/rds/tcp/rds_tcp_rcvbuf would
instead modify the socket's sk_sndbuf and would leave sk_rcvbuf untouched.

Fixes: c6a58ffed536 ("RDS: TCP: Add sysctl tunables for sndbuf/rcvbuf on rds-tcp socket")
Signed-off-by: William Kucharski <william.kucharski@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rds/tcp.c b/net/rds/tcp.c
index abf19c0..5327d13 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -500,7 +500,7 @@
 		sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
 	}
 	if (rtn->rcvbuf_size > 0) {
-		sk->sk_sndbuf = rtn->rcvbuf_size;
+		sk->sk_rcvbuf = rtn->rcvbuf_size;
 		sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
 	}
 	release_sock(sk);