Added core_pair_topic flag.  Removed UpdateMembership and GetMembership calls.

This flag must also be added to the helm charts to work correctly.

VOL-1828

Change-Id: Id992c31b04e54468a94cb5bebcb779600f592ecf
diff --git a/rw_core/config/config.go b/rw_core/config/config.go
index 9671f1a..41d96f4 100644
--- a/rw_core/config/config.go
+++ b/rw_core/config/config.go
@@ -51,6 +51,7 @@
 	default_DefaultRequestTimeout     = int64(500)
 	default_CoreTimeout               = int64(500)
 	default_CoreBindingKey            = "voltha_backend_name"
+	default_CorePairTopic             = "rwcore_1"
 )
 
 // RWCoreFlags represents the set of configurations used by the read-write core service
@@ -82,6 +83,7 @@
 	DefaultRequestTimeout     int64
 	DefaultCoreTimeout        int64
 	CoreBindingKey            string
+	CorePairTopic             string
 }
 
 func init() {
@@ -117,6 +119,7 @@
 		LongRunningRequestTimeout: default_LongRunningRequestTimeout,
 		DefaultCoreTimeout:        default_CoreTimeout,
 		CoreBindingKey:            default_CoreBindingKey,
+		CorePairTopic:             default_CorePairTopic,
 	}
 	return &rwCoreFlag
 }
@@ -195,5 +198,8 @@
 	help = fmt.Sprintf("The name of the meta-key whose value is the rw-core group to which the ofagent is bound")
 	flag.StringVar(&(cf.CoreBindingKey), "core_binding_key", default_CoreBindingKey, help)
 
+	help = fmt.Sprintf("Core pairing group topic")
+	flag.StringVar(&cf.CorePairTopic, "core_pair_topic", default_CorePairTopic, help)
+
 	flag.Parse()
 }