[llvm] Revert "AMDGPU: Try constant fold after folding immediate (#141862)" (PR #148197)

[Matt Arsenault via llvm-commits]

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@@ -961,25 +961,3 @@ body:             |
     S_ENDPGM 0, implicit %2, implicit %3
 
 ...
-
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-name:            constant_v_or_b32_uses_subreg_or_0_regression
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arsenm wrote:

No removing tests. Also missing test for the broken case 

https://github.com/llvm/llvm-project/pull/148197