ss: mptcp: print missing info counters

ss: mptcp: print missing info counters

These new counters have been added in different kernel versions:

- v5.12: local_addr_used, local_addr_max

- v5.13: csum_enabled

- v6.5: retransmits, bytes_retrans, bytes_sent, bytes_received,
  bytes_acked

It is interesting to display them if they are available.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/415
Acked-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Andrea Claudi <aclaudi@redhat.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>