[X86][SSE] Shuffle mask decode support for zero extend, scalar float/double...

[X86][SSE] Shuffle mask decode support for zero extend, scalar float/double moves and integer load instructions

This patch adds shuffle mask decodes for integer zero extends (pmovzx** and movq xmm,xmm) and scalar float/double loads/moves (movss/movsd).

Also adds shuffle mask decodes for integer loads (movd/movq).

Differential Revision: http://reviews.llvm.org/D7228

llvm-svn: 227688