[clang] [OpenCL][NVPTX] Don't set calling convention for OpenCL kernel (PR #170170)

[Hongyu Chen via cfe-commits]

XChy wrote:

> This doesn't seem like a right fix. To me it seems like `getDeviceKernelCallingConv` should not return the wrong CC in the first place.

I am unable to determine whether a function is a stub in the context of `getDeviceKernelCallingConv` or `setTargetAttributes`, unless we check the name prefix `__clang_ocl_kern_imp`. It looks like `setOCLKernelStubCallingConvention` should be the one that returns the correct CC of the OpenCL kernel.


https://github.com/llvm/llvm-project/pull/170170