[llvm] RISC-V: Support vectorizing FMINIMUMNUM and FMAXIMUMNUM (PR #135727)

[YunQiang Su via llvm-commits]

wzssyqa wrote:

Please See: https://llvm.org/docs/LangRef.html#standard

For RISC-V and scale, we have
```
fmin/fmax        ->       FMINIMUMNUM/FMAXIMUMNUM          ->        minimumNumber/maximumNumber(2019)
fminm/fmaxm  ->       FMINIMUM/FMAXIMUM                           ->        minimum/minimum(2019)
```

For RISC-V Vector, we have
```
vfmin/vfmax        ->       FMINIMUMNUM/FMAXIMUMNUM          ->        minimumNumber/maximumNumber(2019)
```

Currently, `FMAXNUM/FMINNUM`(2008) are set `legal` for RISC-V, which is not correct.
I will remove them in future patches.

https://github.com/llvm/llvm-project/pull/135727