ppc64, aix: Fix failing wasm cctests on Aix platform

src/compiler/ppc/instruction-selector-ppc.cc: ensure that input register
does not alias any temporary registers in VisitWord64ReverseBytes method.

Change-Id: I18ddfc5cbe37ba7551ca25efa59d4973f77ffb02
Reviewed-on: https://chromium-review.googlesource.com/1244617Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#56225}

src/compiler/ppc/instruction-selector-ppc.cc

@@ -941,7 +941,7 @@ void InstructionSelector::VisitWord64ReverseBytes(Node* node) {
   PPCOperandGenerator g(this);
   InstructionOperand temp[] = {g.TempRegister()};
   Emit(kPPC_ByteRev64, g.DefineAsRegister(node),
-       g.UseRegister(node->InputAt(0)), 1, temp);
+       g.UseUniqueRegister(node->InputAt(0)), 1, temp);
 }
 
 void InstructionSelector::VisitWord32ReverseBytes(Node* node) {