[MachineCopyPropagation] Fix comment. NFC

Reviewers: MatzeB, qcolombet, jmolloy, mcrosier

Subscribers: llvm-commits, mcrosier

Differential Revision: http://reviews.llvm.org/D16806

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@259656 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed