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

[Gábor Spaits via llvm-commits]

spaits wrote:

> Revert description gives no rationale. This isn't meaningfully testable without a target in need so -1

Yeah I agree that it isn't meaningfully testable without a target. In that case, I think a target should be chosen, on which the patch is demonstrated.

Or is this PR for a downstream target?

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