reset prereqs status on clean.sh
reset prereqs status on clean.sh

when running a clean, we should really reset the prereq status as
well, as this should start us back from zeroish.

Change-Id: I5fae151ab13bcf7fb82feb1e91eed19e0215dc59

openstack-dev/devstack,olivierlemasle/devstack,kplus/devstack-moonshot,atulpatil301/devstack,innodee/openstackk,prithivm/branch01,nawawi/openstack,HPCHub/devstack,costingalan/devstack,tianweizhang/devstack,Mahito/devstack,mssumanth/devstack,samgoon/devstack,jamielennox/devstack,srics/devstack,rushiagr/devstack,pombredanne/devstack,BSJAIN92/OpenStack,upadhyay-prashant/devstack,bljgaurav/openstack-test,noironetworks/devstack,group-policy/devstack,ozamiatin/devstack,rushiagr/devstack,promptworks/devstack,affo/devstack,atulpatil301/devstack,prithivm/branch01,TwinkleChawla/devstack,parul24/devstack,dtroyer/devstack,wenhuizhang/devstack,pczerkas/devstack,neerja28/Devstack_GlusterFS,noironetworks/devstack,eshnil2000/devstack,herrsechs/devstack,LoHChina/devstack,vsham20/devstack,vishnugonela/devstack,ozamiatin/devstack,virtualopensystems/devstack,flavio-fernandes/devstack,Mahito/devstack,mmasaki/devstack,bswartz/devstack,upadhyay-prashant/devstack,olivierlemasle/devstack,pczerkas/devstack,nuxeh/devstack,sc68cal/devstack,varunarya10/devstack,liuquansheng47/devstack,openstack-dev/devstack,dirkmueller/devstack,richliu/devstack,LoHChina/devstack,andrewrothstein/devstack,pacinete/devstack,pombredanne/devstack,bigswitch/devstack,avvocatodemarchis/devstack,varunarya10/devstack,eharney/devstack,sc68cal/devstack,samgoon/devstack,tianweizhang/devstack,williamthegrey/devstack,group-policy/devstack,BSJAIN92/OpenStack,NaokiMiyata/devstack,Juniper/devstack,richliu/devstack,neerja28/Devstack_GlusterFS,dirkmueller/devstack,mssumanth/devstack,dtroyer/devstack,kplus/devstack-moonshot,nawawi/openstack,CloudServer/devstack,CloudServer/devstack,affo/devstack,herrsechs/devstack,mmasaki/devstack,mc2014/devstack,j4/devstack,bljgaurav/openstack-test,pacinete/devstack,avvocatodemarchis/devstack,andrewrothstein/devstack,liuquansheng47/devstack,NaokiMiyata/devstack,flavio-fernandes/devstack,bq-xiao/devstack,mc2014/devstack,wenhuizhang/devstack,parul24/devstack,bigswitch/devstack,bswartz/devstack,nuxeh/devstack,bq-xiao/devstack,HPCHub/devstack,thomasem/devstack,sequenceiq/devstack,eharney/devstack,TwinkleChawla/devstack,costingalan/devstack,vsham20/devstack,sequenceiq/devstack,promptworks/devstack,vishnugonela/devstack,JioCloud/devstack,thomasem/devstack,j4/devstack