fix find torch

[caikun-pjlab]

Motivation and Context

适配pytorch2.2的时候，在dipu里面find_package(torch)，如果重复find_package，会有如下报错：

解决方法：如果已经Torch_FOUND，则不需要重新find_package

Description

Use cases (Optional)

BC-breaking (Optional)

Checklist

Before PR:

• [ ] I have read and followed the workflow indicated in the Contributors.md to create this PR.
• [ ] Pre-commit or linting tools indicated in Contributors.md are used to fix the potential lint issues.
• [ ] Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
• [ ] New functionalities are covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• [ ] The documentation has been modified accordingly, including docstring or example tutorials.

After PR:

• [ ] CLA has been signed and all committers have signed the CLA in this PR.