[clang] [RISCV] Update counters to version 2p0 (PR #66323)

[Jianjian Guan via cfe-commits]

jacquesguan wrote:

> Your commit bumps both the counter and timer extension, which makes your commit message inaccurate.

I think Counters in RISCV ISA include both "Zicntr" and "Zihpm", https://github.com/riscv/riscv-isa-manual/blob/main/src/counters.adoc.

https://github.com/llvm/llvm-project/pull/66323