VOL-908 OpenOLT - delete OLT

Change-Id: I51f3e76e4a6d9f7a184d0b6168663949f541e53b
diff --git a/voltha/adapters/openolt/openolt.py b/voltha/adapters/openolt/openolt.py
index 634040d..288155c 100644
--- a/voltha/adapters/openolt/openolt.py
+++ b/voltha/adapters/openolt/openolt.py
@@ -178,6 +178,7 @@
         handler = self.devices[device.id]
         handler.delete()
         del self.devices[device.id]
+        return device
 
     def get_device_details(self, device):
         log.debug('get_device_details', device=device)