PHIElimination: Remove wrong comment; NFC

The comment was contradicting the code. Looking at history the feature
was implemented a day after the comment was written without dropping the
comment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@344005 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed