MIPS64: Fix build after r22709.

BUG=
R=paul.lind@imgtec.com

Review URL: https://codereview.chromium.org/430223002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22764 ce2b1a6d-e550-0410-aec6-3dcde31c8c00