[clang] [CUDA][HIP] Fix deduction guide (PR #69366)

[Yaxun Liu via cfe-commits]

yxsamliu wrote:

Recently I encountered another deduction guide issue for CUDA/HIP:

https://github.com/ROCm/ROCm/issues/5646

I came up with another fix which I think is simpler and more compatible with C++, that is, to treat deduction guide as host+device like a common C++ entity for CUDA/HIP, whereas we limit host/device-correctness check to the functions, without extending it to deduction guide. I will open another PR and close this PR soon.

https://github.com/llvm/llvm-project/pull/69366