block: rename request_queue slab cache

Name the cache after the actual name of the struct.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

block/blk-core.c

@@ -3513,7 +3513,7 @@ int __init blk_dev_init(void)
 	request_cachep = kmem_cache_create("blkdev_requests",
 			sizeof(struct request), 0, SLAB_PANIC, NULL);
 
-	blk_requestq_cachep = kmem_cache_create("blkdev_queue",
+	blk_requestq_cachep = kmem_cache_create("request_queue",
 			sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
 
 	return 0;