sp-init: Run only on nodes in the tempest group

Limit the sp-init actions to be performed only on nodes with OpenStack.

Change-Id: I203d424f488cde35ce636ca475ae2934aa55a591
diff --git a/playbooks/sp-init.yaml b/playbooks/sp-init.yaml
index af24788..2862b1b 100644
--- a/playbooks/sp-init.yaml
+++ b/playbooks/sp-init.yaml
@@ -48,7 +48,7 @@
       shell:
         cmd: ps awwfux
 
-- hosts: all
+- hosts: tempest
   tasks:
     - name: sp-examine-pwd
       shell: