CVE-2026-64331 usbip: vudc: fix NULL deref in vep_dequeue()

In the Linux kernel, the following vulnerability has been resolved: usbip: vudc: fix NULL deref in vepdequeue vepallocrequest wasn't initializing vrequest-udc, so cancellations on the FunctionFS AIO path were arriving in vepdequeue without a valid UDC reference. Since vrequest-udc is never actual...