[llvm] AMDGPU: Fix inst-selection of large scratch offsets with sgpr base (PR #110256)

[Petar Avramovic via llvm-commits]

petar-avramovic wrote:

### Merge activity

* **Sep 30, 4:43 AM EDT**: @petar-avramovic started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/110256).


https://github.com/llvm/llvm-project/pull/110256