Revert "[SLP] Fix a check for main/alternate interchanged instruction" (#151997)

This reverts commit 3ee8d04.

Revert reason: FAILED build for openmp-offload-amdgpu-runtime-2 
https://lab.llvm.org/buildbot/#/builders/10/builds/10827

Author: mhalk

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -1238,12 +1238,6 @@ class InstructionsState {
     BinOpSameOpcodeHelper Converter(MainOp);
     if (!Converter.add(I) || !Converter.add(MainOp))
       return nullptr;
-    if (!Converter.hasCandidateOpcode(MainOp->getOpcode()) && isAltShuffle()) {
-      BinOpSameOpcodeHelper AltConverter(AltOp);
-      if (AltConverter.add(I) && AltConverter.add(AltOp) &&
-          AltConverter.hasCandidateOpcode(AltOp->getOpcode()))
-        return AltOp;
-    }
     if (Converter.hasAltOp() && !isAltShuffle())
       return nullptr;
     return Converter.hasAltOp() ? AltOp : MainOp;