[llvm] Store sysreg names in-line with their descriptors. (PR #119157)

[Craig Topper via llvm-commits]

https://github.com/topperc approved this pull request.

LGTM. This looks like the most straightfoward thing to do given the current tablegen capabilities.

I think we might be able to remove the barely used DeprecatedName from RISCV by adding additional rows and a IsDeprecatedName bool. I can look at that as a follow.

https://github.com/llvm/llvm-project/pull/119157