MIPS: Fix deoptimization entry table when branch cannot reach.

This fixes failures when table has more than 8192 entries, and preserves
optimization to have 2 instructions per entry.

TEST=mozilla/regress-398085-01
BUG=
R=paul.lind@imgtec.com

Review URL: https://codereview.chromium.org/477623002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23131 ce2b1a6d-e550-0410-aec6-3dcde31c8c00