spi/fsl-espi: fix the return value judgment of irq_of_parse_and_map.

Signed-off-by: Hou Zhiqiang <b48286@freescale.com>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-fsl-espi.c

@@ -705,7 +705,7 @@ static int of_fsl_espi_probe(struct platform_device *ofdev)
 		goto err;
 
 	irq = irq_of_parse_and_map(np, 0);
-	if (!ret) {
+	if (!irq) {
 		ret = -EINVAL;
 		goto err;
 	}