Revert "drm/amdgpu: init iommu after amdkfd device init"

Revert "drm/amdgpu: init iommu after amdkfd device init"

This reverts commit 56b522f4668167096a50c39446d6263c96219f5f.

A user reported that this commit breaks the integrated gpu of his
notebook, causing a black screen. He was able to bisect the problematic
commit and verified that by reverting it the notebook works again.
He also confirmed that kernel 6.8.1 also works on his device, so the
upstream commit itself seems to be ok.

An amdgpu developer (Alex Deucher) confirmed that this patch should
have never been ported to 5.15 in the first place, so revert this
commit from the 5.15 stable series.

Reported-by: Barry Kauler <bkauler@gmail.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20240523173031.4212-1-W_Armin@gmx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>