[llvm] [llvm][RISCV] Handle miscompile of fma in zvfbfa codegen (PR #192412)

[Brandon Wu via llvm-commits]

4vtomat wrote:

> LGTM. Maybe PR title could be updated to specify it's widening fma?

oops I forgot to put "widening", thanks for reminding!

https://github.com/llvm/llvm-project/pull/192412