fix typo in helpers.ext

Change-Id: I3bdb6ae026600e8ce6f0d08aca5e0fb79746ae89
diff --git a/tcp_tests/helpers/ext.py b/tcp_tests/helpers/ext.py
index 8dbf832..7999201 100644
--- a/tcp_tests/helpers/ext.py
+++ b/tcp_tests/helpers/ext.py
@@ -45,7 +45,7 @@
     'salt_deployed',
     'common_services_deployed',
     'oss_deployed',
-    'drivetrain_deployed'
+    'drivetrain_deployed',
     'openstack_deployed',
     'sl_deployed',
     'virtlet_deployed',