Added "drivers" to cells that defined ONOS_APPS.

Change-Id: I8e7cbea037ea09504662fb17ef328b547d21050a
diff --git a/tools/test/cells/ec2 b/tools/test/cells/ec2
index ff7d08d..3d64be2 100644
--- a/tools/test/cells/ec2
+++ b/tools/test/cells/ec2
@@ -15,4 +15,4 @@
 export OC6=192.168.200.106
 export OC7=192.168.200.107
 
-export ONOS_APPS=null,intentperf
+export ONOS_APPS="drivers,null,intentperf"