Fix check for credentials

Change-Id: Ic6fb2befcbad5a50e909a221da67927eff7d1cb5
diff --git a/tests/functional/Voltha_PODTests.robot b/tests/functional/Voltha_PODTests.robot
index cffd591..8c712d9 100644
--- a/tests/functional/Voltha_PODTests.robot
+++ b/tests/functional/Voltha_PODTests.robot
@@ -601,7 +601,7 @@
         ${bng_ip}=    Get Variable Value    ${dst['noroot_ip']}
         ${bng_user}=    Get Variable Value    ${dst['noroot_user']}
         ${bng_pass}=    Get Variable Value    ${dst['noroot_pass']}
-        Pass Execution If    not ("${bng_ip}" and "${bng_user}" and "${bng_pass}")
+        Pass Execution If    "${bng_ip}" == "${NONE}" or "${bng_user}" == "${NONE}" or "${bng_pass}" == "${NONE}"
         ...    Skipping test: credentials for BNG login required in deployment config
 
         ${stdout}    ${stderr}    ${rc}=    Execute Remote Command    which mausezahn tcpdump