[llvm] [RISCV] Remove skipFunction from RISCVVMV0Elimination. (PR #136080)

[Sam Elliott via llvm-commits]

lenary wrote:

Do we need an isRequired function for the NPM too? It doesn't look like this is a NPM Pass yet, but that is coming for backend passes. 

https://github.com/llvm/llvm-project/pull/136080