[llvm] [BOLT] Delete unnecessary instructions (PR #189297)

[Kito Cheng via llvm-commits]

https://github.com/kito-cheng approved this pull request.

It's Kito, I am working on RISC-V backend and RISC-V psABI for long time, and this change is correct and LGTM, but I not bolt guy, so plz make sure any bolt reviewer is happy with this change as well before merge.

https://github.com/llvm/llvm-project/pull/189297