VOL-776: Fix for openolt DHCP handling

Change-Id: I60f3e4cb50804752ad0326b16ceea5c42f5b6eee
diff --git a/voltha/adapters/openolt/openolt_device.py b/voltha/adapters/openolt/openolt_device.py
index e6d4222..a62f1e5 100644
--- a/voltha/adapters/openolt/openolt_device.py
+++ b/voltha/adapters/openolt/openolt_device.py
@@ -801,7 +801,7 @@
         self.stub.FlowAdd(flow)
         time.sleep(0.1) # FIXME
 
-    def add_dhcp_trap(intf_id, onu_id, self, classifier, action):
+    def add_dhcp_trap(self, intf_id, onu_id, classifier, action):
 
         self.log.info('add dhcp trap', classifier=classifier, action=action)