[llvm] Fix build break when building RISCVInstrInfo.cpp with MSVC (PR #110342)

[Daniel Paoliello via llvm-commits]

dpaoliello wrote:

Looks like CI is running VS 2019:
```
The C compiler identification is MSVC 19.29.30154.0
```

And I'm using VS 2022:
```
> cl --version
Microsoft (R) C/C++ Optimizing Compiler Version 19.41.34120 for x64
```

https://github.com/llvm/llvm-project/pull/110342