[bugfix] bugfix for npu free memory (#9640)

* Improve NPU performance

* Improve NPU performance

* Improve NPU performance

* Improve NPU performance

* [bugfix] bugfix for npu free memory

* [bugfix] bugfix for npu free memory

* [bugfix] bugfix for npu free memory

---------
Co-authored-by: 蒋硕 <jiangshuo9@h-partners.com>
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>

src/diffusers/training_utils.py

@@ -284,7 +284,7 @@ def free_memory():
     elif torch.backends.mps.is_available():
         torch.mps.empty_cache()
     elif is_torch_npu_available():
-        torch_npu.empty_cache()
+        torch_npu.npu.empty_cache()
 
 
 # Adapted from torch-ema https://github.com/fadel/pytorch_ema/blob/master/torch_ema/ema.py#L14