RDMA/nes: Fix FIN state handling under error conditions

During cluster testing, one QP was not closed, as FIN is not handled
properly when its rexmit count expires or in some cases when RST is is
received after sending FIN.  The reason is that the cm_id does not get
decremented under these conditions.

Signed-off-by: Faisal Latif <faisal.latif@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>