drm: don't double-free on driver load error

All instances of drm_dev_register are followed by drm_dev_free on
failure. Don't free dev->control/render/primary on failure, as they will
be freed by drm_dev_free since commit 8f6599da8e (drm: delay minor
destruction to drm_dev_free()). Instead unplug them.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reported-and-tested-by: Bruno Prémont <bonbons@linux-vserver.org>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_stub.c

@@ -566,11 +566,11 @@ err_unload:
 	if (dev->driver->unload)
 		dev->driver->unload(dev);
 err_primary_node:
-	drm_put_minor(dev->primary);
+	drm_unplug_minor(dev->primary);
 err_render_node:
-	drm_put_minor(dev->render);
+	drm_unplug_minor(dev->render);
 err_control_node:
-	drm_put_minor(dev->control);
+	drm_unplug_minor(dev->control);
 err_agp:
 	if (dev->driver->bus->agp_destroy)
 		dev->driver->bus->agp_destroy(dev);