Fix a SSE2 intrinsics typo

Full discourse at:

  http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20131104/092514.html
  http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-November/068124.html

Patch by Dimitry Andric and Alexey Dokuchaev!