staging/lustre/ptlrpc: missing wakeup for ptlrpc_check_set

This patch changes a few things:

- There is no guarantee that request_out_callback will happen
  before reply_in_callback, if a request got reply and unlinked
  reply buffer before request_out_callback is called, then the
  thread waiting on ptlrpc_request_set will miss wakeup event.

  This may seriously impact performance of some IO workloads or
  result in RPC timeout

- To make code more easier to understand, this patch changes
  action-bits "rq_req_unlink" and "rq_reply_unlink" to
  status-bits "rq_req_unlinked" and "rq_reply_unlinked"

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-on: http://review.whamcloud.com/12158
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5696


Reviewed-by: Johann Lombardi <johann.lombardi@intel.com>
Reviewed-by: Li Wei <wei.g.li@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>