build(deps): bump third_party/litex from 95b310e to c122573

Bumps [third_party/litex](https://github.com/enjoy-digital/litex) from `95b310e` to `c122573`.
- [Commits](enjoy-digital/litex@95b310e...c122573)

---
updated-dependencies:
- dependency-name: third_party/litex
  dependency-type: direct:production
...

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