Revert r133452: "Emit movq for 64-bit register to XMM register moves..."

Revert r133452: "Emit movq for 64-bit register to XMM register moves..."

This is breaking compiler-rt and llvm-gcc builds on MacOSX when not using
the integrated assembler.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133524 91177308-0d34-0410-b5e6-96231b3b80d8