usb: ulpi: Fix debugfs directory leak

In the Linux kernel, the following vulnerability has been resolved: usb: ulpi: Fix debugfs directory leak The ULPI per-device debugfs root is named after the ulpi device's parent, but ulpi_unregister_interface tries to remove a debugfs directory named after the ulpi device itself. This results in the directory sticking around and preventing subsequent (deferred) probes from succeeding. Change the directory name to match the ulpi device.