[BLOCK] Get rid of request_queue_t typedef

Some of the code has been gradually transitioned to using the proper
struct request_queue, but there's lots left. So do a full sweet of
the kernel and get rid of this typedef and replace its uses with
the proper type.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

include/linux/loop.h

@@ -63,7 +63,7 @@ struct loop_device {
 	struct task_struct	*lo_thread;
 	wait_queue_head_t	lo_event;
 
-	request_queue_t		*lo_queue;
+	struct request_queue	*lo_queue;
 	struct gendisk		*lo_disk;
 	struct list_head	lo_list;
 };