ehci: kick async schedule on wakeup

Kick async schedule when we get a wakeup
notification from a usb device.
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/usb/hcd-ehci.c

@@ -852,6 +852,8 @@ static void ehci_wakeup(USBPort *port)
         USBPort *companion = s->companion_ports[port->index];
         if (companion->ops->wakeup) {
             companion->ops->wakeup(companion);
+        } else {
+            qemu_bh_schedule(s->async_bh);
         }
     }
 }