[mips] Add support for .cpsetup

Summary:
Patch by Robert N. M. Watson
His work was sponsored by: DARPA, AFRL

Small corrections by myself.

CC: theraven, matheusalmeida

Differential Revision: http://llvm-reviews.chandlerc.com/D3199

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204924 91177308-0d34-0410-b5e6-96231b3b80d8