MIPS: Initialize CodeStubInterfaceDescriptor in the constructor.

Port r23773 (9b5b258)

BUG=
R=paul.lind@imgtec.com

Review URL: https://codereview.chromium.org/553783004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23782 ce2b1a6d-e550-0410-aec6-3dcde31c8c00