mtd: spear_smi: use for_each_child_of_node() macro

Use for_each_child_of_node() macro instead of open coding it.
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200914061324.3230-1-miaoqinglang@huawei.com

drivers/mtd/devices/spear_smi.c

@@ -793,7 +793,7 @@ static int spear_smi_probe_config_dt(struct platform_device *pdev,
 				     struct device_node *np)
 {
 	struct spear_smi_plat_data *pdata = dev_get_platdata(&pdev->dev);
-	struct device_node *pp = NULL;
+	struct device_node *pp;
 	const __be32 *addr;
 	u32 val;
 	int len;
@@ -812,7 +812,7 @@ static int spear_smi_probe_config_dt(struct platform_device *pdev,
 		return -ENOMEM;
 
 	/* Fill structs for each subnode (flash device) */
-	while ((pp = of_get_next_child(np, pp))) {
+	for_each_child_of_node(np, pp) {
 		pdata->np[i] = pp;
 
 		/* Read base-addr and size from DT */