Revert "[AMDGPU] SelectionDAG divergence tracking should take into account Target divergency. (#144947)"
This reverts commit 8ac7210b7f0ad49ae7809bf6a9faf2f7433384b0.
This breaks the building the AArch64 backend, e.g. see
https://github.com/llvm/llvm-project/pull/144947
Revert to unbreak the build.
Also reverts follow-up commits 1e76f012db3ccfaa05e238812e572b5b6d12c17e.