Allow multiple registrator to register classes

Change-Id: I35a56b889c45b936bb022a9639702fda21619258

Author: Vidyashree-Huawei

runtime/src/main/java/org/onosproject/yang/runtime/impl/DefaultYangModelRegistry.java

@@ -150,8 +150,7 @@ public void registerModel(ModelRegistrationParam param) throws
         if (!modelIdStore.containsKey(id)) {
             updateRegClassStore(param);
             modelIdStore.put(id, model);
-        } else if ((info != null) &&
-                   (!registerClassStore.containsValue(info.getModuleClass()))) {
+        } else if (info != null) {
             updateRegClassStore(param);
         } else {
             throw new IllegalArgumentException("ModelId " + id + " already exist");