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

[Krzysztof Parzyszek via llvm-commits]

kparzysz wrote:

This is an alternative to https://github.com/llvm/llvm-project/pull/87405, since I wanted to focus on the issues causing the assertion to fail.

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