[llvm] [LV] Add test for reverse load with scatter store. nfc (PR #189928)

[Mel Chen via llvm-commits]

Mel-Chen wrote:

> Can you also copy this test to the RISC-V folder? I think the same benchmark timberwolfmc was failing on the RISC-V buildbots too so would be good to have coverage there as well: https://lab.llvm.org/buildbot/#/builders/210/builds/9728

Sure. 5245488c19176a98a6b9f42a0ee8b864b79c5aca

https://github.com/llvm/llvm-project/pull/189928