selftests: mptcp: display warnings on one line

Before we had this in case of SYN retransmissions:

  (...)
  # ns4 MPTCP -> ns2 (10.0.1.2:10034      ) MPTCP	(duration  1201ms) [ OK ]
  # ns4 MPTCP -> ns2 (dead:beef:1::2:10035) MPTCP	(duration  1242ms) [ OK ]
  # ns4 MPTCP -> ns2 (10.0.2.1:10036      ) MPTCP	ns2-60143c00-cDZWo4 SYNRX: MPTCP -> MPTCP: expect 11, got
  # 13
  # (duration  6221ms) [ OK ]
  # ns4 MPTCP -> ns2 (dead:beef:2::1:10037) MPTCP	(duration  1427ms) [ OK ]
  # ns4 MPTCP -> ns3 (10.0.2.2:10038      ) MPTCP	(duration   881ms) [ OK ]
  (...)

Now we have:

  (...)
  # ns4 MPTCP -> ns2 (10.0.1.2:10034      ) MPTCP	(duration  1201ms) [ OK ]
  # ns4 MPTCP -> ns2 (dead:beef:1::2:10035) MPTCP	(duration  1242ms) [ OK ]
  # ns4 MPTCP -> ns2 (10.0.2.1:10036      ) MPTCP	(duration  6221ms) [ OK ] WARN: SYNRX: expect 11, got 13
  # ns4 MPTCP -> ns2 (dead:beef:2::1:10037) MPTCP	(duration  1427ms) [ OK ]
  # ns4 MPTCP -> ns3 (10.0.2.2:10038      ) MPTCP	(duration   881ms) [ OK ]
  (...)

So we put everything on one line, keep the durations and "OK" aligned
and removed duplicated info to short the warning.

Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>