[llvm] [RISCV] Support Zvfbfa codegen (PR #161158)

[Brandon Wu via llvm-commits]

4vtomat wrote:

The original PR is split into 2 PRs, this is codegen PR and other is here: https://github.com/llvm/llvm-project/pull/164094

https://github.com/llvm/llvm-project/pull/161158