Remove an unnecessary duplicate initialization of TLOF from the Mips

AsmPrinter. This was reinitializing the Mangler after we moved the
Mangler down to TLOF and causing us to have two different unnamed
global values accessed with the same name.

This should fix the problems on the ubsan tests here:
http://lab.llvm.org:8011/builders/clang-cmake-mips/builds/15307

llvm-svn: 282675