LU-9725 quota: always deregister lwp

LU-9725 quota: always deregister lwp

qsd should always deregiter lwp upon finish no matter qsd_exp was
set before, otherwise the item will stay on the list, but qsd has
been freed.

Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Change-Id: I0d6206f2f2bc8177d0aa35b350f534d85eab1c03
Reviewed-on: https://review.whamcloud.com/28356
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>