Remove the NULL state
Remove the NULL state

NULL and NOSTATE seems to be redundant, plus the NULL state haven't been
used anywhere.

Change-Id: Iaf20dcc661c4334fe2b140306ee2310a83478bb6

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