block: move blkdev_{get,put} _no_open prototypes out of blkdev.h

These are only to be used by block internal code.  Remove the comment
as we grew more users due to reworking block device node opening.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250423053810.1683309-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Christoph Hellwig

block/blk.h

@@ -94,6 +94,9 @@ static inline void blk_wait_io(struct completion *done)
 		wait_for_completion_io(done);
 }
 
+struct block_device *blkdev_get_no_open(dev_t dev);
+void blkdev_put_no_open(struct block_device *bdev);
+
 #define BIO_INLINE_VECS 4
 struct bio_vec *bvec_alloc(mempool_t *pool, unsigned short *nr_vecs,
 		gfp_t gfp_mask);

include/linux/blkdev.h

@@ -1671,10 +1671,6 @@ int bd_prepare_to_claim(struct block_device *bdev, void *holder,
 		const struct blk_holder_ops *hops);
 void bd_abort_claiming(struct block_device *bdev, void *holder);
 
-/* just for blk-cgroup, don't use elsewhere */
-struct block_device *blkdev_get_no_open(dev_t dev);
-void blkdev_put_no_open(struct block_device *bdev);
-
 struct block_device *I_BDEV(struct inode *inode);
 struct block_device *file_bdev(struct file *bdev_file);
 bool disk_live(struct gendisk *disk);