block: Remove references to __device_add_disk()

Since commit d1254a874971 ("block: remove support for delayed queue
registrations"), function __device_add_disk() has been replaced with
device_add_disk(), so fix up comments.

Signed-off-by: John Garry <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

block/genhd.c

···
  * partitions associated with the gendisk, and unregisters the associated
  * request_queue.
  *
- * This is the counter to the respective __device_add_disk() call.
+ * This is the counter to the respective device_add_disk() call.
  *
  * The final removal of the struct gendisk happens when its refcount reaches 0
  * with put_disk(), which should be called after del_gendisk(), if
- * __device_add_disk() was used.
+ * device_add_disk() was used.
  *
  * Drivers exist which depend on the release of the gendisk to be synchronous,
  * it should not be deferred.
···
  *
  * This function releases all allocated resources of the gendisk.
  *
- * Drivers which used __device_add_disk() have a gendisk with a request_queue
+ * Drivers which used device_add_disk() have a gendisk with a request_queue
  * assigned. Since the request_queue sits on top of the gendisk for these
  * drivers we also call blk_put_queue() for them, and we expect the
  * request_queue refcount to reach 0 at this point, and so the request_queue