Add Cvtdq2ps macro.
Add pblendw/vpblendw.

Change-Id: I5c8232d17c220fbbb4845cbfad4ce765f0bbbb90
Reviewed-on: https://chromium-review.googlesource.com/961973
Commit-Queue: Jing Bao <jing.bao@intel.com>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52255}