[llvm] [AMDGPU][GlobalISel] Align `selectVOP3PMadMixModsImpl` with the `SelectionDAG` counterpart (PR #110168)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,23 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -global-isel -mtriple=amdgcn -mcpu=gfx908 -denormal-fp-math=preserve-sign -verify-machineinstrs %s -o - | FileCheck %s
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arsenm wrote:

Don't need -verify-machininstrs. Also prefer to just use the explicit denormal-fp-math-f32 attribute in the test itself 

https://github.com/llvm/llvm-project/pull/110168