[llvm] [RISCV][TTI] Properly model odd vector sized LD/ST operations (PR #100436)

[Philip Reames via llvm-commits]

preames wrote:

> Hold off on reviewing this, I think I may have pushed a bad commit.

Corrected version pushed.  Sorry, I appear to have screwed up a rebase/squash for the first version posted.  

https://github.com/llvm/llvm-project/pull/100436