Voltha Alarm Filters: Added hooks to suppress alarms at the adapter

- Updates based on review comments
- Fixed indentation

Change-Id: Icd1c35919d1c23b86094d4684aaaafb7bae57754
diff --git a/voltha/adapters/broadcom_onu/broadcom_onu.py b/voltha/adapters/broadcom_onu/broadcom_onu.py
index b8f7d7f..e02c9ed 100644
--- a/voltha/adapters/broadcom_onu/broadcom_onu.py
+++ b/voltha/adapters/broadcom_onu/broadcom_onu.py
@@ -144,6 +144,11 @@
     def receive_inter_adapter_message(self, msg):
         log.info('receive_inter_adapter_message', msg=msg)
 
+    def suppress_alarm(self, filter):
+        raise NotImplementedError()
+
+    def unsuppress_alarm(self, filter):
+        raise NotImplementedError()
 
 class BroadcomOnuHandler(object):