build(deps): bump litex/deps/litex from cdaf8af to 6c6cfea

Bumps [litex/deps/litex](https://github.com/enjoy-digital/litex) from `cdaf8af` to `6c6cfea`.
- [Commits](enjoy-digital/litex@cdaf8af...6c6cfea)

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

Signed-off-by: dependabot[bot] <[email protected]>