Simplify LTOModule::makeLTOModule a bit. NFC.

Just call parseBitcodeFile instead of getLazyBitcodeModule followed by
materializeAllPermanently.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216461 91177308-0d34-0410-b5e6-96231b3b80d8