[llvm] AMDGPU: Enable RELA for PAL target (PR #128516)

[Jay Foad via llvm-commits]

jayfoad wrote:

Also should update the documentation: https://github.com/llvm/llvm-project/blob/96c87a16a507207e839f20b668ccd51dd2db6123/llvm/docs/AMDGPUUsage.rst?plain=1#L2598

https://github.com/llvm/llvm-project/pull/128516