io_uring: deduplicate io_queue_sqe() call sites

There are two call sites of io_queue_sqe() in io_submit_sqe(), combine
them into one, because io_queue_sqe() is inline and we don't want to
bloat binary, and will become even bigger

   text    data     bss     dec     hex filename
  92126   13986       8  106120   19e88 ./fs/io_uring.o
  91966   13986       8  105960   19de8 ./fs/io_uring.o

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/506124b8e767f0a4576f7a459f6aea3d13fb4dda.1632516769.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -7117,20 +7117,18 @@ fail_req:
 		link->last->link = req;
 		link->last = req;
 
+		if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK))
+			return 0;
 		/* last request of a link, enqueue the link */
-		if (!(req->flags & (REQ_F_LINK | REQ_F_HARDLINK))) {
-			link->head = NULL;
-			io_queue_sqe(head);
-		}
-	} else {
-		if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) {
-			link->head = req;
-			link->last = req;
-		} else {
-			io_queue_sqe(req);
-		}
+		link->head = NULL;
+		req = head;
+	} else if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) {
+		link->head = req;
+		link->last = req;
+		return 0;
 	}
 
+	io_queue_sqe(req);
 	return 0;
 }