[MC] Rename EmitFill to emitFill

This is to match the overloaded variants as well as the new style.

Differential Revision: http://reviews.llvm.org/D20690

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271359 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed