[VOL-3117] Read KV store data path prefix from an environment variable

- voltha-lib-go reads the KVStoreDataPrefix from env variable, so removed the command-line flag in voltha-go
- also removed unused corepair topic flag
Change-Id: Ibe8403bf187126b587a92cd9c58aa6d923f84cd0
diff --git a/rw_core/core/device/manager.go b/rw_core/core/device/manager.go
index 17ac266..c7af54a 100755
--- a/rw_core/core/device/manager.go
+++ b/rw_core/core/device/manager.go
@@ -60,11 +60,11 @@
 }
 
 //NewManagers creates the Manager and the Logical Manager.
-func NewManagers(dbPath *model.Path, adapterMgr *adapter.Manager, kmp kafka.InterContainerProxy, endpointMgr kafka.EndpointManager, corePairTopic, coreInstanceID string, defaultCoreTimeout time.Duration) (*Manager, *LogicalManager) {
+func NewManagers(dbPath *model.Path, adapterMgr *adapter.Manager, kmp kafka.InterContainerProxy, endpointMgr kafka.EndpointManager, coreTopic, coreInstanceID string, defaultCoreTimeout time.Duration) (*Manager, *LogicalManager) {
 	deviceMgr := &Manager{
 		rootDevices:             make(map[string]bool),
 		kafkaICProxy:            kmp,
-		adapterProxy:            remote.NewAdapterProxy(kmp, corePairTopic, endpointMgr),
+		adapterProxy:            remote.NewAdapterProxy(kmp, coreTopic, endpointMgr),
 		coreInstanceID:          coreInstanceID,
 		dbPath:                  dbPath,
 		dProxy:                  dbPath.Proxy("devices"),