[DAGCombiner] remove redundant fold for X*1.0; NFC
[DAGCombiner] remove redundant fold for X*1.0; NFC

This is handled at node creation time (similar to X/1.0)
after:
rL357029
(no fast-math-flags needed)

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@368443 91177308-0d34-0410-b5e6-96231b3b80d8

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