sp-init: Fix var definition location

Change-Id: Ida755d9fe64ea958dd69704914ec728391f83496
diff --git a/playbooks/sp-init.yaml b/playbooks/sp-init.yaml
index c753b5d..6bd31e7 100644
--- a/playbooks/sp-init.yaml
+++ b/playbooks/sp-init.yaml
@@ -3,7 +3,6 @@
   vars:
     host_id: "{{ hostvars['controller']['nodepool']['external_id'] }}"
     storprep_filename: "/tmp/storprep-bootstrap-{{ host_id }}.sh"
-    homedir: "{{ ansible_env.HOME }}"
   tasks:
     - name: storprep
       when: do_storprep is defined and do_storprep
@@ -54,6 +53,8 @@
             cmd: ps awwfux
 
 - hosts: tempest
+  vars:
+    homedir: "{{ ansible_env.HOME }}"
   tasks:
     - name: sp-examine-pwd
       shell: