[llvm] [RISCV] Add scheduler definitions for SpacemiT-X60 (PR #137343)

[Mark Zhuang via llvm-commits]

zqb-all wrote:

> Folks, we wrote a probe to double-check all latencies in the scheduler and updated the latencies accordingly. We tested it on two different boards to confirm the numbers.

Hi @mikhailramalho  , is "probe" referring to "llvm-exegesis", or does it refer to another independent program?

https://github.com/llvm/llvm-project/pull/137343