MIPS: Fix bug introduced by r15640.

This bug causes segfault in the octane benchmark,
because the deoptimization entries do not fit in the
deopt table.
This change increases the table entry size.

TEST=octane benchmark

BUG=

Review URL: https://codereview.chromium.org/19381004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15695 ce2b1a6d-e550-0410-aec6-3dcde31c8c00