use new watcher insterad of iface_cast

Signed-off-by: Nyichengzhao <yichengzhao1@huawei.com>
Change-Id: Ib82f1d7bf9c2d6df8a9c58aa164a062c26f66c57

services/param/watcher/proxy/watcher_manager_stub.cpp

@@ -44,7 +44,8 @@ int32_t WatcherManagerStub::OnRemoteRequest(uint32_t code,
             auto remote = data.ReadRemoteObject();
             // 0 is invalid watcherId
             uint32_t id = data.ReadUint32();
-            uint32_t remoteWatcherId = AddRemoteWatcher(id, iface_cast<IWatcher>(remote));
+            sptr<IWatcher> watcher = new WatcherProxy(remote);
+            uint32_t remoteWatcherId = AddRemoteWatcher(id, watcher);
             reply.WriteUint32(remoteWatcherId);
             break;
         }