[clang] [llvm] [RISCV] Add Spacemit X100 processor definition (PR #173988)

[Craig Topper via cfe-commits]

topperc wrote:

Please do not force push in PRs without a good reason. https://llvm.org/docs/GitHub.html#rebasing-pull-requests-and-force-pushes

https://github.com/llvm/llvm-project/pull/173988