Fix seed vm deprovision

The libvirt_vm_vcpus and libvirt_vm_memory_mb variables are required by
the stackhpc.libvirt-vm role even when setting libvirt_vm_state to
absent. Without these variables, `kayobe seed vm deprovision` fails with
the following error:

    FAILED! => {"msg": "'libvirt_vm_vcpus' is undefined"}

Change-Id: If74f4229cf777328e3a02794067caae7aa731a80

ansible/seed-vm-deprovision.yml

@@ -10,6 +10,8 @@
         name: "{{ seed_hostvars.seed_vm_name }}-configdrive"
         pool: "{{ seed_hostvars.seed_vm_pool }}"
       libvirt_vm_name: "{{ seed_hostvars.seed_vm_name }}"
+      libvirt_vm_memory_mb: "{{ seed_hostvars.seed_vm_memory_mb }}"
+      libvirt_vm_vcpus: "{{ seed_hostvars.seed_vm_vcpus }}"
       libvirt_vm_volumes: "{{ seed_hostvars.seed_vm_volumes + [seed_vm_configdrive_volume] }}"
       libvirt_vm_state: "absent"
       become: True