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

[Luke Lau via llvm-commits]

https://github.com/lukel97 approved this pull request.

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

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