[clang] [llvm] [RISCV] Add processor definition for SpacemiT-X60 (PR #94564)

[Michael Maitland via cfe-commits]

michaelmaitland wrote:

I want to circle back to a comment made by @asb [here](https://github.com/llvm/llvm-project/pull/70294#issuecomment-1782282361):
>  it's obvious that commercial designs with active support should go in

Since this is in BPi-F3, I think that it constitutes as a commercial design. Will this core have active support on the LLVM side?

https://github.com/llvm/llvm-project/pull/94564