[llvm] RISCV: Remove shouldForceRelocation and unneeded relocations (PR #140692)

[Sam Elliott via llvm-commits]

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

I agree these new names are better for distinguishing branch vs linker relaxation. One nit, but you can skip it if you want.

https://github.com/llvm/llvm-project/pull/140692