selftests: mptcp: fix ACKRX debug message

Info from received MPCapable SYN were printed instead of the ones from
received MPCapable 3rd ACK.

Fixes: fed61c4b ("selftests: mptcp: make 2nd net namespace use tcp syn cookies unconditionally")
Signed-off-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/net/mptcp/mptcp_connect.sh

@@ -502,7 +502,7 @@ do_transfer()
 		echo "${listener_ns} SYNRX: ${cl_proto} -> ${srv_proto}: expect ${expect_synrx}, got ${stat_synrx_now_l}"
 	fi
 	if [ $expect_ackrx -ne $stat_ackrx_now_l ] ;then
-		echo "${listener_ns} ACKRX: ${cl_proto} -> ${srv_proto}: expect ${expect_synrx}, got ${stat_synrx_now_l}"
+		echo "${listener_ns} ACKRX: ${cl_proto} -> ${srv_proto}: expect ${expect_ackrx}, got ${stat_ackrx_now_l} "
 	fi
 
 	if [ $retc -eq 0 ] && [ $rets -eq 0 ];then