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 <dan.carpenter@oracle.com>
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/usbip/vudc_sysfs.c

@@ -201,7 +201,7 @@ static ssize_t usbip_status_show(struct device *dev,
 	int status;
 
 	if (!udc) {
-		dev_err(&udc->pdev->dev, "no device");
+		dev_err(dev, "no device");
 		return -ENODEV;
 	}
 	spin_lock_irq(&udc->ud.lock);