Do Materialize Floating Point in Mips Fast-Isel

Summary:
Implement materialize of floating point literals in Mips Fast-Isel

Reopened version of D3659

Test Plan: simplestorefp1.ll

Reviewers: dsanders

Reviewed By: dsanders

Differential Revision: http://reviews.llvm.org/D4071

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210546 91177308-0d34-0410-b5e6-96231b3b80d8