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

[Sergio Afonso via cfe-commits]

================
@@ -31,6 +31,15 @@ class Triple;
 // back-end to TableGen to create these clean tables.
 namespace AMDGPU {
 
+/// Address space values for AMD GPUs
+enum AddrSpace {
+  Generic = 0,
----------------
skatrak wrote:

I think it would be good to prefix these names with something so that uses are self-documenting. For example, something like AS_{GENERIC, GLOBAL, ...} or ADDRESS_{GENERIC, GLOBAL, ...}, if we use the enums below as reference.

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