[TargetLowering][NFC] prepareUREMEqFold(): fixup comment
[TargetLowering][NFC] prepareUREMEqFold(): fixup comment

The comment initially matched the code, but the code was incorrect
and was fixed after the initial revert back back when it was introduced,
but the comment was never updated.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@368701 91177308-0d34-0410-b5e6-96231b3b80d8

GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm