floppy: remove duplicated code in redo_fd_request()

duplicated code in redo_fd_request(),
unlock_fdc() function has the same code "do_floppy = NULL" inside.
Signed-off-by: Yufeng Wang <wangyufeng@kylinos.cn>
Suggested-by: Denis Efremov <efremov@linux.com>
Link: https://lore.kernel.org/r/20240319014219.7812-1-wangyufeng@kylinos.cnSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/floppy.c

@@ -2787,7 +2787,6 @@ static void redo_fd_request(void)
 		pending = set_next_request();
 		spin_unlock_irq(&floppy_lock);
 		if (!pending) {
-			do_floppy = NULL;
 			unlock_fdc();
 			return;
 		}