[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>
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index fc27f6c..aff661f 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -469,7 +469,7 @@
 "    Change the ubd device name to \"hd\".\n\n"
 );
 
-static void do_ubd_request(request_queue_t * q);
+static void do_ubd_request(struct request_queue * q);
 
 /* Only changed by ubd_init, which is an initcall. */
 int thread_fd = -1;
@@ -1081,7 +1081,7 @@
 }
 
 /* Called with dev->lock held */
-static void do_ubd_request(request_queue_t *q)
+static void do_ubd_request(struct request_queue *q)
 {
 	struct io_thread_req *io_req;
 	struct request *req;