usb: usbip: Avoid NULL pointer dereference in case of error

One line above we have checked that udc is NULL so we shouldn't
dereference it while printing error message.

Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Krzysztof Opasiak <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/usbip/vudc_sysfs.c

···
 	int status;
 
 	if (!udc) {
-		dev_err(&udc->pdev->dev, "no device");
+		dev_err(dev, "no device");
 		return -ENODEV;
 	}
 	spin_lock_irq(&udc->ud.lock);