[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>

drivers/block/xd.c

@@ -298,7 +298,7 @@ static u_char __init xd_detect (u_char *controller, unsigned int *address)
 }
 
 /* do_xd_request: handle an incoming request */
-static void do_xd_request (request_queue_t * q)
+static void do_xd_request (struct request_queue * q)
 {
 	struct request *req;