Revert rL345395: [X86][SSE] Move 2-input limit up from getFauxShuffleMask to...

Revert rL345395: [X86][SSE] Move 2-input limit up from getFauxShuffleMask to resolveTargetShuffleInputs
Makes no difference to actual shuffle decoding yet, but merges all the existing limits in one place for when proper support is fixed.
........
Its been reported that this is causing out of trunk failures.

llvm-svn: 345451