[x64] add missing disassm of pcmpeqd

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/658063003

Patch from Weiliang Lin <weiliang.lin@intel.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24680 ce2b1a6d-e550-0410-aec6-3dcde31c8c00