[llvm] [flang] [clang] [NFC][AMDGPU] Move address space enum to LLVM directory (PR #73944)

[Dominik Adamski via llvm-commits]

DominikAdamski wrote:

The address spaces for AMDGPU defined [here](https://github.com/llvm/llvm-project/blob/main/llvm/lib/Target/AMDGPU/AMDGPU.h#L395-L456) contain more types of address spaces in comparison to the enum defined in clang. Is it ok to extend number of address space types for clang?

https://github.com/llvm/llvm-project/pull/73944