Add YANG specific annotations to voltha.proto for alarmfilterkey.  Without it YANG parsing of the voltha proto file will fail

Change-Id: I7b3a53de4c2e451937583471ea15b019931100f1
diff --git a/voltha/protos/voltha.proto b/voltha/protos/voltha.proto
index d871d8a..8dcdba1 100644
--- a/voltha/protos/voltha.proto
+++ b/voltha/protos/voltha.proto
@@ -41,6 +41,8 @@
 
 
 message AlarmFilterRuleKey {
+    option (yang_child_rule) = MOVE_TO_PARENT_LEVEL;
+    
     enum AlarmFilterRuleKey {
         id = 0;
         type = 1;