net: fix qemu_flush_queued_packets() in presence of a hub

Do not return after net_hub_flush(). Always flush callee network client
incoming queue.
Signed-off-by: NSergey Fedorov <s.fedorov@samsung.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

net/net.c

@@ -443,7 +443,6 @@ void qemu_flush_queued_packets(NetClientState *nc)
         if (net_hub_flush(nc->peer)) {
             qemu_notify_event();
         }
-        return;
     }
     if (qemu_net_queue_flush(nc->incoming_queue)) {
         /* We emptied the queue successfully, signal to the IO thread to repoll