drm/nouveau: correctly pair hwmon_init and hwmon_fini

I broke this with my commit
07cfe0e7a820ecad078c04e9c2a102521709145d

This fixes fdo #33434

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nouveau_pm.c b/drivers/gpu/drm/nouveau/nouveau_pm.c
index fb846a3..f05c0cd 100644
--- a/drivers/gpu/drm/nouveau/nouveau_pm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_pm.c
@@ -443,7 +443,7 @@
 	struct nouveau_pm_engine *pm = &dev_priv->engine.pm;
 
 	if (pm->hwmon) {
-		sysfs_remove_group(&pm->hwmon->kobj, &hwmon_attrgroup);
+		sysfs_remove_group(&dev->pdev->dev.kobj, &hwmon_attrgroup);
 		hwmon_device_unregister(pm->hwmon);
 	}
 #endif