MIPS: Disable cctest/test-simplified-lowering/LowerStringOps_to_call_and_wordeq because of turbofan after r23616.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/531853002

Patch from Balazs Kilvady <balazs.kilvady@imgtec.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23627 ce2b1a6d-e550-0410-aec6-3dcde31c8c00