spi: spi-amd: Fix a NULL vs IS_ERR() check in amd_spi_probe()

In case of error, the function devm_ioremap_resource() returns ERR_PTR()
and never returns NULL. The NULL test in the return value check should
be replaced with IS_ERR().

Fixes: bbb336f3 ("spi: spi-amd: Add AMD SPI controller driver support")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20200429025426.167664-1-weiyongjun1@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-amd.c

@@ -266,10 +266,9 @@ static int amd_spi_probe(struct platform_device *pdev)
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	amd_spi->io_remap_addr = devm_ioremap_resource(&pdev->dev, res);
-
-	if (!amd_spi->io_remap_addr) {
+	if (IS_ERR(amd_spi->io_remap_addr)) {
+		err = PTR_ERR(amd_spi->io_remap_addr);
 		dev_err(dev, "error %d ioremap of SPI registers failed\n", err);
-		err = -ENOMEM;
 		goto err_free_master;
 	}
 	dev_dbg(dev, "io_remap_address: %p\n", amd_spi->io_remap_addr);