mptcp: use mptcp_win_from_space helper

The MPTCP dedicated win_from_space helper mptcp_win_from_space() is defined
in protocol.h, use it in mptcp_rcv_space_adjust() instead of using the TCP
one. Here scaling_ratio is the same as msk->scaling_ratio.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/mptcp/protocol.c

@@ -2046,7 +2046,7 @@ static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied)
 		if (rcvbuf > sk->sk_rcvbuf) {
 			u32 window_clamp;
 
-			window_clamp = __tcp_win_from_space(scaling_ratio, rcvbuf);
+			window_clamp = mptcp_win_from_space(sk, rcvbuf);
 			WRITE_ONCE(sk->sk_rcvbuf, rcvbuf);
 
 			/* Make subflows follow along.  If we do not do this, we