Minor sympy usage fix in fbcode (#93171)
Summary: To supports older versions of sympy.
Test Plan:
```
buck2 run @//mode/opt @//mode/inplace -c python.package_style=inplace -c fbcode.enable_gpu_sections=true //caffe2/benchmarks/dynamo:torchbench -- -dcuda --performance --inductor --only hf_T5
```
Differential Revision: D42812188
Pull Request resolved: https://github.com/pytorch/pytorch/pull/93171
Approved by: https://github.com/eellison
