[mips] Remove dead code from MipsPassConfig

Found by GCC's -Wunused-function.

Patch by Kim Gräsman.

Differential revision: https://reviews.llvm.org/D50612

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339847 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed