[clang] [Clang][HIP] Deprecate the AMDGCN_WAVEFRONT_SIZE macros (PR #112849)

[Fabian Ritter via cfe-commits]

ritter-x2a wrote:

@AlexVlx @jhuber6 @arsenm  is there a dependence between this deprecation PR and #114481, or can we already go ahead with the deprecation of the macro via this PR?

https://github.com/llvm/llvm-project/pull/112849