[llvm] Revert "[GlobalISel] Add support for lowering byref attribute" (PR #96784)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

If you express interest in `byref`,  then restart the PR with an AMDGPU test.

`out of tree targets.`does not free you from tests.

https://github.com/llvm/llvm-project/pull/96784