[llvm] [RISCV] Shrink uses of coalesced vsetvlis (PR #98286)

[Luke Lau via llvm-commits]

lukel97 wrote:

DefReg is a different register, it's the output VL, this is for the input AVL. But now that you mention it, we were also duplicating the liveintervals update for the AVL too. We already handle it for the normal case, but the bug was ultimately caused by this case here where we continue early for two consecutive vsetvlis with no pseudos in between:

https://github.com/llvm/llvm-project/pull/98286/files#diff-a186cfa1b7676c0a95a09935007221c321cfc52ce54b85d15064963d413725a3R1657-R1661

I've removed that redundant case so we're only updating the *AVL* in one place. 

https://github.com/llvm/llvm-project/pull/98286