[llvm] [AMDGPU] Add an option to completely disable kernel argument preload (PR #153975)

[Shilei Tian via llvm-commits]

shiltian wrote:

Yes, I have. As I understand it, `amdgpu-kernarg-preload-count` only controls how many explicit kernel arguments are preloaded. It doesn't affect existing `inreg` arguments or implicit kernel arguments.

https://github.com/llvm/llvm-project/pull/153975