[llvm] [AMDGPU] Fix GFX1250 hazard: S_SET_VGPR_MSB dropped (PR #184904)

[Shilei Tian via llvm-commits]

https://github.com/shiltian commented:

Is it possible that we only check whether the insertion point is a S_SETREG_IMM32_B32 instead of using a boolean variable?

https://github.com/llvm/llvm-project/pull/184904