[llvm] [AMDGPU] Allow shinking instruction with dead sdst (PR #68028)

[Stanislav Mekhanoshin via llvm-commits]

rampitec wrote:

> Dead carry out with immediate carry in sounds like a missing globalisel combine that doesn't need to be worked around

This may explain impact on gisel only.

https://github.com/llvm/llvm-project/pull/68028