usb: Convert uses of usb_create()

Replace

    dev = usb_create(bus, type_name);
    ...
    object_property_set_bool(OBJECT(dev), true, "realized", &err);

by

    dev = isa_new(type_name);
    ...
    usb_realize_and_unref(dev, bus, &err);

Recent commit "qdev: New qdev_new(), qdev_realize(), etc." explains
why.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200610053247.1583243-28-armbru@redhat.com>
3 files changed