[llvm] [RISCV] Re-model RVV comparison instructions (PR #88868)

[Craig Topper via llvm-commits]

topperc wrote:

I think, a long time ago I wondered if we should have a version of the compare pseudos that had the dest tied to v0 to avoid the early clobber. And let the 3 address instruction conversion break it if it needed. Similar to the _TIED instructions we have for VWADD.WV.

https://github.com/llvm/llvm-project/pull/88868