fixes to data-collator patching for padding-free plugin

Signed-off-by: 1000960000 user <[email protected]>

plugins/instruct-lab/src/fms_acceleration_ilab/framework_plugin_padding_free.py

@@ -207,7 +207,7 @@ def prepare(self, *args, device_placement=None):
             # Replace the collate_fn in dataloader
             dataloader.collate_fn = DataCollatorWithFlattening()
 
-            return dataloader
+            return _old_prepare(dataloader)
 
         accelerator.prepare = MethodType(prepare, accelerator)