[X86] Remove lines that set v8f32 FP_ROUND/FP_EXTEND to Legal under AVX512. NFCI
[X86] Remove lines that set v8f32 FP_ROUND/FP_EXTEND to Legal under AVX512. NFCI

We don't do this for narrow vectors under AVX or SSE features. We also don't set them to Expand like we do for many vectors op. Nor does TargetLoweringBase.cpp. This leads me to believe these default to Legal.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@319103 91177308-0d34-0410-b5e6-96231b3b80d8

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