[llvm] [RISCV] Remove CalleeSavedInfo for Zcmp/save-restore-libcalls registers (PR #79535)

[Wang Pengcheng via llvm-commits]

https://github.com/wangpc-pp approved this pull request.

The code looks fine, but I am not familiar with this part, so please wait for another approval.

https://github.com/llvm/llvm-project/pull/79535