[clang] [llvm] [NVPTX][clang] Remove scoped atomic intrinsics; use atomicrmw/cmpxchg (PR #200735)

[Justin Lebar via cfe-commits]

jlebar wrote:

> I think thanks to some recent work by @akshayrdeodhar this family of intrinsics is redundant and should probably be completely removed

OK, done!

https://github.com/llvm/llvm-project/pull/200735