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}