[PATCH v2] riscv: Sync hwprobe definitions with Linux kernel

[Yao Zihong]

> Add some new Linux RISC-V hwprobe definitions with the upstream linux
> kernel. This is useful to support dl-hwcaps-subdirs for RISC-V and use
> the new key RISCV_HWPROBE_KEY_MISALIGNED_SCALAR_PERF and
> RISCV_HWPROBE_KEY_MISALIGNED_VECTOR_PERF to better determine multiple
> implementations for IFUNC in the future.

Hi Yangyu,

Thanks for the patch.

I have a small WIP prototype for dl-hwcaps-subdirs on RISC-V, using
rva20u64 as an initial example to explore a general approach that could
extend to rva22u64/rva23u64.

Before I send an RFC, I’d like to check whether anyone is already working
on a subdir implementation beyond this header sync; happy to align or
hold off to avoid duplication.

Best,
Zihong