drm/amd/display: Remove superfluous drm_mode_config_cleanup

It's already being released by DRM core through devm
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210512142648.666476-15-andrey.grodzovsky@amd.com

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -3764,7 +3764,6 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 
 static void amdgpu_dm_destroy_drm_device(struct amdgpu_display_manager *dm)
 {
-	drm_mode_config_cleanup(dm->ddev);
 	drm_atomic_private_obj_fini(&dm->atomic_obj);
 	return;
 }