usb: Replace device_destroy bus op with a child_detach port op

usb: Replace device_destroy bus op with a child_detach port op

Note this fixes 2 things in one go, first of all the device_destroy bus
op should be a device_detach bus op, as pending async packets from the
device should be cancelled on detach not on destroy.

Secondly having this as a bus op won't work with companion controllers, since
then there will be 1 bus driven by the ehci controller and thus 1 set of bus
ops, but the device being detached may be downstream of a handed over port.
Making the detach of a downstream device a port op allows the ehci controller
to forward this to the companion controller port for handed over ports.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>