LU-522 lod: do not ignore degraded flag of ost.

LU-522 lod: do not ignore degraded flag of ost.

QoS allocation algorithm ignores degraded flag of OSTs.
Added a check for degraded ost flag in lod_alloc_qos().

Seagate-bug-id: MRP-2820

Signed-off-by: Jadhav Vikram <jadhav.vikram@seagate.com>
Change-Id: Ib2390518afff7b9bd459ce64bf609af99071e46d
Reviewed-on: http://es-gerrit.xyus.xyratex.com:8080/9966
Tested-by: Jenkins
Reviewed-by: Ujjwal Lanjewar <ujjwal.lanjewar@seagate.com>
Reviewed-by: Vladimir Saveliev <vladimir.saveliev@seagate.com>
Tested-by: Parinay Vijayprakash Kondekar <parinay.kondekar@seagate.com>
Reviewed-on: http://review.whamcloud.com/20747
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>