[llvm] [NVPTX] Fix for device function pointer having the same name as generated callprototype (PR #205639)

[Alex MacLean via llvm-commits]

AlexMaclean wrote:

Is this really a problem in any real world program? If we're just operating on hypotheticals, what's to stop someone from doing `@"$L__prototype_0" = addrspace(1) global ptr null, align 8`?

https://github.com/llvm/llvm-project/pull/205639