[Fix] Fix boxes.scalar_type in nms_npu (#2731)

Author: momo609

mmcv/ops/csrc/pytorch/npu/nms_npu.cpp

@@ -4,7 +4,7 @@ using namespace NPU_NAME_SPACE;
 using namespace std;
 
 Tensor nms_npu(Tensor boxes, Tensor scores, float iou_threshold, int offset) {
-  TORCH_CHECK((boxes.scalar_type == at::ScalarType::Float),
+  TORCH_CHECK((boxes.scalar_type() == at::ScalarType::Float),
               "The type of boxes tensor passed in nms_npu should be float");
   int64_t offset_64 = offset;
   at::Tensor iou_threshold_y = at_npu::native::OpPreparation::ApplyTensor(