LU-4336 quota: improper assert in osc_quota_chkdq()

LU-4336 quota: improper assert in osc_quota_chkdq()

In osc_quota_chkdq(), we should never try to access oqi found
from hash, since it could have been freed by osc_quota_setdq().

Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Change-Id: Ia73cf89cb5bbd730fa6f0a00e44771f733b2baa6
Reviewed-on: http://review.whamcloud.com/8460
Reviewed-by: Johann Lombardi <johann.lombardi@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>