use getMinions directly

getMinions was patched to expect expression directly

Change-Id: I3de13e58cd5f4077af78081db150e1c7819c4a17
diff --git a/openstack-compute-upgrade.groovy b/openstack-compute-upgrade.groovy
index 768f055..fcccebc 100644
--- a/openstack-compute-upgrade.groovy
+++ b/openstack-compute-upgrade.groovy
@@ -14,7 +14,6 @@
 def salt = new com.mirantis.mk.Salt()
 
 def saltMaster
-def targetAll = ['expression': TARGET_SERVERS, 'type': 'compound']
 def targetTestSubset
 def targetLiveSubset
 def targetLiveAll
@@ -33,7 +32,7 @@
         }
 
         stage('List target servers') {
-            minions = salt.getMinions(saltMaster, targetAll)
+            minions = salt.getMinions(saltMaster, TARGET_SERVERS)
 
             if (minions.isEmpty()) {
                 throw new Exception("No minion was targeted")