Fix DEBUG-mode GPU builds (#5778)

Fix for DEBUG mode

This commit fixes issue #5777

src/treelearner/cuda/cuda_single_gpu_tree_learner.cpp

@@ -94,8 +94,8 @@ void CUDASingleGPUTreeLearner::BeforeTrain() {
   }
 
   #ifdef DEBUG
-  CopyFromCUDADeviceToHost<score_t>(host_gradients.data(), gradients_, static_cast<size_t>(num_data_), __FILE__, __LINE__);
-  CopyFromCUDADeviceToHost<score_t>(host_hessians.data(), hessians_, static_cast<size_t>(num_data_), __FILE__, __LINE__);
+  CopyFromCUDADeviceToHost<score_t>(host_gradients_.data(), gradients_, static_cast<size_t>(num_data_), __FILE__, __LINE__);
+  CopyFromCUDADeviceToHost<score_t>(host_hessians_.data(), hessians_, static_cast<size_t>(num_data_), __FILE__, __LINE__);
   #endif  // DEBUG
 
   const data_size_t* leaf_splits_init_indices =

src/treelearner/cuda/cuda_single_gpu_tree_learner.hpp

@@ -68,7 +68,7 @@ class CUDASingleGPUTreeLearner: public SerialTreeLearner {
 
   void SelectFeatureByNode(const Tree* tree);
 
-  #ifdef DEUBG
+  #ifdef DEBUG
   void CheckSplitValid(
     const int left_leaf, const int right_leaf,
     const double sum_left_gradients, const double sum_right_gradients);