rbd: add __init/__exit annotations

Add __init/__exit annotation to init/cleanup helpers
which are only called once in the module.
Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

drivers/block/rbd.c

@@ -6067,7 +6067,7 @@ static ssize_t rbd_remove_single_major(struct bus_type *bus,
  * create control files in sysfs
  * /sys/bus/rbd/...
  */
-static int rbd_sysfs_init(void)
+static int __init rbd_sysfs_init(void)
 {
 	int ret;
 
@@ -6082,13 +6082,13 @@ static int rbd_sysfs_init(void)
 	return ret;
 }
 
-static void rbd_sysfs_cleanup(void)
+static void __exit rbd_sysfs_cleanup(void)
 {
 	bus_unregister(&rbd_bus_type);
 	device_unregister(&rbd_root_dev);
 }
 
-static int rbd_slab_init(void)
+static int __init rbd_slab_init(void)
 {
 	rbd_assert(!rbd_img_request_cache);
 	rbd_img_request_cache = KMEM_CACHE(rbd_img_request, 0);