[RISCV][NewPM] Port RISCVCodeGenPrepare to the new pass manager#168381

asb merged 2 commits intollvm:mainllvm/llvm-project:mainfrom

asb:2025q4-riscv-npm-riscvcodegenprepareasb/llvm-project:2025q4-riscv-npm-riscvcodegenprepareCopy head branch name to clipboard