[clang] [llvm] [RISCV]Add RVA23.1 and RVB23.1 experimental profiles (PR #217199)

[Pengcheng Wang via llvm-commits]

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wangpc-pp wrote:

```suggestion
def RVA23P1S64 : RISCVExperimentalProfile<"rva23p1s64", RVA23S64Features>;
def RVB23P1S64 : RISCVExperimentalProfile<"rvb23p1s64", RVB23S64Features>;
```

We just need to support these strings and the features are identical to `rva23s64` and `rvb23s64`.


https://github.com/llvm/llvm-project/pull/217199