spi: fsl-(e)spi: Fix checking return value of devm_ioremap_resource

devm_ioremap_resource() returns ERR_PTR on error.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c
index db82c87..c27124a 100644
--- a/drivers/spi/spi-fsl-espi.c
+++ b/drivers/spi/spi-fsl-espi.c
@@ -674,8 +674,8 @@
 	mpc8xxx_spi = spi_master_get_devdata(master);
 
 	mpc8xxx_spi->reg_base = devm_ioremap_resource(dev, mem);
-	if (!mpc8xxx_spi->reg_base) {
-		ret = -ENOMEM;
+	if (IS_ERR(mpc8xxx_spi->reg_base)) {
+		ret = PTR_ERR(mpc8xxx_spi->reg_base);
 		goto err_probe;
 	}