usb: gadget: goku_udc: fix memory leak in goku_probe()

Memory allocated for goku_udc device is not deallocated at error
paths in goku_probe(), because gadget_release() destructor
is not registered yet.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/goku_udc.c

@@ -1838,6 +1838,8 @@ static int goku_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 err:
 	if (dev)
 		goku_remove (pdev);
+	/* gadget_release is not registered yet, kfree explicitly */
+	kfree(dev);
 	return retval;
 }