Push driver with pipeconfId when available

Change-Id: I9dfebdd123c0efdf044bcc85177ef6b9658ee1af
diff --git a/tools/dev/mininet/bmv2.py b/tools/dev/mininet/bmv2.py
index 0c0fc15..a8034c2 100644
--- a/tools/dev/mininet/bmv2.py
+++ b/tools/dev/mininet/bmv2.py
@@ -131,7 +131,7 @@
     def getDeviceConfig(self, srcIP):
 
         basicCfg = {
-            "driver": "bmv2"
+            "driver": ("bmv2:" + self.pipeconfId) if self.pipeconfId != None else "bmv2"
         }
 
         if self.longitude and self.latitude: