[CORD-3191] Remove old pmc-olt ref. Replace with voltha

Change-Id: I661c00526f377e99aac25037276019e1f724c36e
diff --git a/src/test/utils/Cluster.py b/src/test/utils/Cluster.py
index 1b3a05c..4f762ea 100644
--- a/src/test/utils/Cluster.py
+++ b/src/test/utils/Cluster.py
@@ -1697,7 +1697,7 @@
             cls.device_dict = { "devices" : {
                         "{}".format(did) : {
                               "basic" : {
-                                    "driver" : "pmc-olt"
+                                    "driver" : "voltha"
                                     }
                               }
                         },
@@ -1712,7 +1712,7 @@
           network_cfg = { "devices" : {
                   "{}".format(did) : {
                         "basic" : {
-                              "driver" : "pmc-olt"
+                              "driver" : "voltha"
                               }
                         }
                   },