Bump llvm-project from 2f9fa50 to f670e5d

Bumps [llvm-project](https://github.com/Xilinx/llvm-project) from `2f9fa50` to `f670e5d`.
- [Commits](Xilinx/llvm-project@2f9fa50...f670e5d)

---
updated-dependencies:
- dependency-name: llvm-project
  dependency-type: direct:production
...

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