LU-5259 ptlrpc: request gets stuck in UNREGISTERING phase

Exit condition from UNREGISTERING phase is releasing of
both reply and bulk buffers.

Call ptlrpc_unregister_bulk() if ptlrpc_unregister_reply()
wasn't completed in async mode before switching to
UNREGISTERING phase.

Change-Id: Ia0420aecf0391e1a45063add2aa75bb4b3caa5a6
Xyratex-bug-id: MRP-1960
Signed-off-by: Andriy Skulysh <Andriy_Skulysh@xyratex.com>
Reviewed-on: http://review.whamcloud.com/10846
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Reviewed-by: Ann Koehler <amk@cray.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>