9P: fix test at the end of p9_write_work()

At the end of p9_write_work() we want to test if there is still data to send.
This means:
- either the current request still has data to send (wsize != 0)
- or there are requests in the unsent queue
Signed-off-by: NSimon Derr <simon.derr@bull.net>
Signed-off-by: NEric Van Hensbergen <ericvh@gmail.com>

net/9p/trans_fd.c

@@ -492,7 +492,7 @@ static void p9_write_work(struct work_struct *work)
 	if (m->wpos == m->wsize)
 		m->wpos = m->wsize = 0;
 
-	if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
+	if (m->wsize || !list_empty(&m->unsent_req_list)) {
 		if (test_and_clear_bit(Wpending, &m->wsched))
 			n = POLLOUT;
 		else