Update resource manager for fixed stevedore issue
Update resource manager for fixed stevedore issue

Stevedore commit 69e17801a3f0cf37257069da7dc83e2608f31aa5 fixed a
known issue in conductor.resource_manager.

This patch updates the Ironic code to use stevedore's new accessor.

Change-Id: I0f57831a70368afb5ea321c0e607f762d464c2a0

SauloAislan/ironic,pshchelo/ironic,hpproliant/ironic,naototty/vagrant-lxc-ironic,ramineni/myironic,citrix-openstack-build/ironic,faizan-barmawer/openstack_ironic,bacaldwell/ironic,SauloAislan/ironic,Tan0/ironic,openstack/ironic,redhat-openstack/ironic,devananda/ironic,ionutbalutoiu/ironic,openstack/ironic,JioCloud/ironic,Tehsmash/ironic,NaohiroTamura/ironic,ionutbalutoiu/ironic,NaohiroTamura/ironic,supermari0/ironic,rackerlabs/ironic,rdo-management/ironic,naototty/vagrant-lxc-ironic,citrix-openstack-build/ironic,dims/ironic,dims/ironic,froyobin/ironic,pshchelo/ironic,varunarya10/ironic,debayanray/ironic_backup,bacaldwell/ironic,naterh/ironic