[Hi-Dream LoRA] fix bug in validation (#11439)

remove unnecessary pipeline moving to cpu in validation
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>

examples/dreambooth/train_dreambooth_lora_hidream.py

@@ -236,7 +236,6 @@ def log_validation(
                 }
             )
 
-    pipeline.to("cpu")
     del pipeline
     free_memory()