This reverts commit e490d60a.

This causes hangs on SI when DC is enabled and errors on driver
reboot and power off cycles.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3216
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/2755Reviewed-by: Yang Wang <kevinyang.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>