Fixes the sd adapter in forge experiments (#1484)

Copied from github.com//pull/1441, tested manually via
forge

---------

Co-authored-by: Allen Wang <[email protected]>

Author: allenwang28

torchtitan/experiments/forge/engine.py

@@ -215,7 +215,11 @@ def __init__(self, job_config: ForgeJobConfig):
             lr_schedulers=self.lr_schedulers,
             states={"train_state": self},
             checkpoint_config=job_config.checkpoint,
-            sd_adapter=self.train_spec.state_dict_adapter,
+            sd_adapter=(
+                self.train_spec.state_dict_adapter(model_args)
+                if self.train_spec.state_dict_adapter
+                else None
+            ),
         )
 
         loss_parallel_enabled = (