[llvm] [NFC] Reduce fragility of swdev503538-move-to-valu… test (PR #170702)

[Jay Foad via llvm-commits]

jayfoad wrote:

> This MIR test was generated from swdev503538-move-to-valu-stack-srd-physreg.ll using: `llc -stop-before=si-fix-sgpr-copies -O0`

Can you add `-simplify-mir`?

https://github.com/llvm/llvm-project/pull/170702