!2751 fix mix target device id

Merge pull request !2751 from kisnwang/fix-mix-target-device-id-r0.5

mindspore/ccsrc/vm/backend.cc

@@ -353,7 +353,10 @@ void MsBackend::CreateOtherSession(const std::string &target) {
   if (other_sess_ == nullptr) {
     MS_LOG(EXCEPTION) << "Session create failed!, please make sure target device:" << target << " is available.";
   }
-  other_sess_->Init(0);
+  auto context_ptr = MsContext::GetInstance();
+  MS_EXCEPTION_IF_NULL(context_ptr);
+  uint32_t device_id = context_ptr->device_id();
+  other_sess_->Init(device_id);
   other_sess_->RegisterSummaryCallBackFunc(callbacks::SummarySaveCallback);
   other_device_ = target;
 }