Revert "Delete unnecessary arg setting (huggingface#978)" (huggingface#985)

This reverts commit 83c69ec.

Author: yzhang93

apps/stable_diffusion/src/pipelines/pipeline_shark_stable_diffusion_utils.py

@@ -186,6 +186,8 @@ def from_pretrained(
         use_tuned: bool,
     ):
         if import_mlir:
+            # TODO: Delet this when on-the-fly tuning of models work.
+            use_tuned = False
             mlir_import = SharkifyStableDiffusionModel(
                 model_id,
                 ckpt_loc,