CVE-2026-10663 Use-after-free / double-free of the root USB device in the experimental USB host stack

In Zephyr's experimental USB host stack CONFIGUSBHOSTSTACK, usbhdevicedisconnect subsys/usb/host/usbhdevice.c freed the root usbdevice slab object without clearing the cached pointer ctx-root. The bus removal handler devremovedhandler subsys/usb/host/usbhcore.c decides what to tear down solely fr...