LiveRangeEdit: Inline markDeadRemat() into only user; NFC

This function was only called from a single place in which we didn't
even need the `if (DeadRemats)` check.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@322230 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed