[RUNTIME][OPENCL] set type_key even when platform is not available (#2741)

Author: kazum

src/runtime/opencl/opencl_device_api.cc

@@ -237,6 +237,7 @@ void OpenCLWorkspace::Init(const std::string& type_key, const std::string& devic
   std::lock_guard<std::mutex> lock(this->mu);
   if (initialized_) return;
   if (context != nullptr) return;
+  this->type_key = type_key;
   // matched platforms
   std::vector<cl_platform_id> platform_ids = cl::GetPlatformIDs();
   if (platform_ids.size() == 0) {
@@ -254,7 +255,6 @@ void OpenCLWorkspace::Init(const std::string& type_key, const std::string& devic
       devices_matched = cl::GetDeviceIDs(platform_id, "cpu");
     }
     if (devices_matched.size() > 0) {
-      this->type_key = type_key;
       this->platform_id = platform_id;
       this->platform_name = cl::GetPlatformInfo(platform_id, CL_PLATFORM_NAME);
       this->device_type = device_type;