[llvm] [RISCV] Restrict combineOp_VLToVWOp_VL w/ bf16 to vfwmadd_vl with zvfbfwma (PR #108798)

[Jia Sun via llvm-commits]

https://github.com/sun-jacobi approved this pull request.

Nice catch! Thank you :)

https://github.com/llvm/llvm-project/pull/108798