[X86] Remove code from combineUIntToFP that tried to favor UINT_TO_FP if legal when zero extending from vXi8/vX816.
[X86] Remove code from combineUIntToFP that tried to favor UINT_TO_FP if legal when zero extending from vXi8/vX816.

The UINT_TO_FP is immediately converted to SINT_TO_FP when the node is re-evaluated because we'll detect that the sign bit is zero.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@319234 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm