block: unexport blk_register_queue

Not actually used in any modular code.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210816123649.601591-1-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

block/blk-sysfs.c

@@ -939,7 +939,6 @@ int blk_register_queue(struct gendisk *disk)
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(blk_register_queue);
 
 /**
  * blk_unregister_queue - counterpart of blk_register_queue()