work on kernel modules reviving

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>
using pthread_once to implement xio_init and xio_shutdown

Signed-off-by: Eyal Salomon <esalomon@mellanox.com>
adding reference counting to fin messages
fin requests can be sent simultanously from peer to peer
disconnection must take place just after all fin completions are done

Signed-off-by: Eyal Salomon <esalomon@mellanox.com>