[NVPTX] Fix some usages of CodeGenOpt::None.
[NVPTX] Fix some usages of CodeGenOpt::None.

NVPTXLowerKernelArgs is required for correctness, so it should not be guarded
by CodeGenOpt::None.

NVPTXPeephole is optimization only, so it should be skipped when
CodeGenOpt::None.



git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@267619 91177308-0d34-0410-b5e6-96231b3b80d8

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