staging: pi433: fix error return code in pi433_probe()

Fix to return negative error code -ENOMEM from cdev alloc failed error
handling case instead of 0, as done elsewhere in this function.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20200428150650.102340-1-weiyongjun1@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/pi433/pi433_if.c

@@ -1230,6 +1230,7 @@ static int pi433_probe(struct spi_device *spi)
 	device->cdev = cdev_alloc();
 	if (!device->cdev) {
 		dev_dbg(device->dev, "allocation of cdev failed");
+		retval = -ENOMEM;
 		goto cdev_failed;
 	}
 	device->cdev->owner = THIS_MODULE;