Improved the operands commute transformation for X86-FMA3 instructions.

All 3 operands of FMA3 instructions are commutable now.

Patch by Slava Klochkov

Reviewers: Quentin Colombet(qcolombet), Ahmed Bougacha(ab).

Differential Revision: http://reviews.llvm.org/D13269

llvm-svn: 252335