staging: lustre: take extra refcount in kiblnd_connreq_done

refcount taken by cmid is not reliable after kiblnd_connreq_done
released the glock because this connection is visible to other
threads, another thread can find and close this connection right
after kiblnd_connreq_done released the glock, if kiblnd_cm_callback
for RDMA_CM_EVENT_DISCONNECTED is called, it can release the
connection refcount taken by cmid. It means the connection could be
destroyed before kiblnd_connreq_done() finish operations on it.

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
ntel-bug-id: https://jira.hpdd.intel.com/browse/LU-7210
Reviewed-on: http://review.whamcloud.com/17527


Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>