[llvm] [LLVM][CodeGen] Fix register lane liveness tracking in RegisterPressure (PR #88892)

[Quentin Colombet via llvm-commits]

https://github.com/qcolombet approved this pull request.

LGTM.
Just double checking, this commit is already exercised by existing tests, right?
Otherwise, could you add a test?

https://github.com/llvm/llvm-project/pull/88892