[export] Remove CallSpec (pytorch#117671)

Summary:

X-link: pytorch/executorch#1618

This is not really being used anywhere

Test Plan: CI

Differential Revision: D52842563

torch/_export/exported_program.py

@@ -1,11 +1,8 @@
-import dataclasses
-from typing import Optional
 import warnings
 
 
 import torch
 import torch.fx
-import torch.utils._pytree as pytree
 
 
 # TODO(ycao): This is added to avoid breaking existing code temporarily.
@@ -32,13 +29,6 @@
 ]
 
 
-# Information to maintain user calling/returning specs
-@dataclasses.dataclass
-class CallSpec:
-    in_spec: Optional[pytree.TreeSpec]
-    out_spec: Optional[pytree.TreeSpec]
-
-
 def _create_graph_module_for_export(root, graph):
     try:
         gm = torch.fx.GraphModule(root, graph)