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 <[e-mail]>
Signed-off-by: Miquel Raynal <[e-mail]>
Link: https://lore.kernel.org/linux-mtd/[e-mail]

drivers/mtd/devices/spear_smi.c

···
 				     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;
···
 		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 */