Adding infrastructure to allow sending messages between adapters
using the adapter-agent event bus.

Change-Id: Ia3654b8944745bc76f8ac4ea3c1439a082979dd4
diff --git a/voltha/adapters/microsemi_olt/microsemi_olt.py b/voltha/adapters/microsemi_olt/microsemi_olt.py
index b98e340..8ac93c5 100644
--- a/voltha/adapters/microsemi_olt/microsemi_olt.py
+++ b/voltha/adapters/microsemi_olt/microsemi_olt.py
@@ -165,6 +165,9 @@
         log.info('packet-out', logical_device_id=logical_device_id,
                  egress_port_no=egress_port_no, msg_len=len(msg))
 
+    def receive_inter_adapter_message(self, msg):
+        raise NotImplementedError()
+
     ##
     # Private methods
     ##