fix SerializeSelectedRows (PaddlePaddle#36543)

* bug fix for  DeserializeSelectedRows. test=develop

* fix bug for SerializeSelectedRows. test=develop

* update. test=develop

paddle/fluid/distributed/service/brpc_utils.cc

@@ -138,23 +138,11 @@ void SerializeSelectedRows(framework::Variable* var,
   var_data->clear();
   var_data->resize(rows->size() * sizeof(int64_t));
   char* data_ptr = const_cast<char*>(var_data->data());
-
-  if (platform::is_cpu_place(tensor->place())) {
-    memcpy(data_ptr, &(*rows)[0], rows->size() * sizeof(int64_t));
-  } else {
-#ifdef PADDLE_WITH_CUDA
-    auto stream =
-        reinterpret_cast<const platform::CUDADeviceContext&>(ctx).stream();
-    memory::Copy(platform::CPUPlace(), data_ptr,
-                 BOOST_GET_CONST(platform::CUDAPlace, tensor->place()),
-                 &(*rows)[0], rows->size() * sizeof(int64_t), stream);
-#endif
-  }
+  memcpy(data_ptr, &((*rows)[0]), rows->size() * sizeof(int64_t));
   var_msg->set_data_type(static_cast<VarMsg::Type>(tensor->type()));
   for (auto& dim : framework::vectorize(tensor->dims())) {
     var_msg->add_dims(dim);
   }
-
   // IO Buffer
   if (platform::is_cpu_place(tensor->place())) {
     auto data_len = tensor->numel() * framework::SizeOfType(tensor->type());