usb-ehci: Clear the portstatus powner bit on device disconnect

According to the EHCI spec port ownership should revert to the EHCI controller
on device disconnect. This fixes the problem of a port getting stuck on USB 1
when using redirection and plugging in a USB 2 device after a USB 1 device
has been redirected.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/hw/usb-ehci.c b/hw/usb-ehci.c
index 75ef71e..cdd7415 100644
--- a/hw/usb-ehci.c
+++ b/hw/usb-ehci.c
@@ -765,6 +765,11 @@
         USBPort *companion = s->companion_ports[port->index];
         companion->ops->detach(companion);
         companion->dev = NULL;
+        /*
+         * EHCI spec 4.2.2: "When a disconnect occurs... On the event,
+         * the port ownership is returned immediately to the EHCI controller."
+         */
+        *portsc &= ~PORTSC_POWNER;
         return;
     }