spi: ep93xx: fix error return code in ep93xx_spi_probe()

Fix to return -ENOMEM in the workqueue create error handling
case instead of 0, as done elsewhere in this function.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/spi/spi-ep93xx.c

@@ -1104,6 +1104,7 @@ static int ep93xx_spi_probe(struct platform_device *pdev)
 	espi->wq = create_singlethread_workqueue("ep93xx_spid");
 	if (!espi->wq) {
 		dev_err(&pdev->dev, "unable to create workqueue\n");
+		error = -ENOMEM;
 		goto fail_free_dma;
 	}
 	INIT_WORK(&espi->msg_work, ep93xx_spi_work);