Updated FOR loop syntax to new robot version

Signed-off-by: Marissa Garza <garzam@us.ibm.com>
Change-Id: Id543440c04974e6cfa8adbb6e8100759cd903d82
diff --git a/lib/pdu/pdu.robot b/lib/pdu/pdu.robot
index 3bd2b56..6c9be1b 100644
--- a/lib/pdu/pdu.robot
+++ b/lib/pdu/pdu.robot
@@ -7,8 +7,9 @@
 Validate Prereq
     [Documentation]  Validate prerequisites for PDU.
     ${PDU_VAR_LIST}=    Create List    PDU_TYPE    PDU_IP  PDU_USERNAME    PDU_PASSWORD    PDU_SLOT_NO
-    : FOR    ${PDU_VAR}    IN    @{PDU_VAR_LIST}
-    \    Should Not Be Empty    ${${PDU_VAR}}   msg=Unable to find variable ${PDU_VAR}
+    FOR    ${PDU_VAR}    IN    @{PDU_VAR_LIST}
+        Should Not Be Empty    ${${PDU_VAR}}   msg=Unable to find variable ${PDU_VAR}
+    END
 
 PDU Power Cycle
     [Documentation]  Perform PDU power cycle.