ARM: imx: use device_initcall for imx_soc_device_init

This is preparation to move imx_soc_device_init to drivers/soc/imx/

There is no reason to must put dt devices under /sys/devices/soc0,
they could also be under /sys/devices/platform, so we could
pass NULL as parent when calling of_platform_default_populate.

Following soc-imx8.c soc-imx-scu.c using device_initcall, need
to change return type to int type for imx_soc_device_init.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/mach-imx/cpu.c

@@ -83,7 +83,7 @@ void __init imx_aips_allow_unprivileged_access(
 	}
 }
 
-struct device * __init imx_soc_device_init(void)
+static int __init imx_soc_device_init(void)
 {
 	struct soc_device_attribute *soc_dev_attr;
 	const char *ocotp_compat = NULL;
@@ -97,7 +97,7 @@ struct device * __init imx_soc_device_init(void)
 
 	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
 	if (!soc_dev_attr)
-		return NULL;
+		return -ENOMEM;
 
 	soc_dev_attr->family = "Freescale i.MX";
 
@@ -224,18 +224,24 @@ struct device * __init imx_soc_device_init(void)
 	soc_dev_attr->revision = kasprintf(GFP_KERNEL, "%d.%d",
 					   (imx_soc_revision >> 4) & 0xf,
 					   imx_soc_revision & 0xf);
-	if (!soc_dev_attr->revision)
+	if (!soc_dev_attr->revision) {
+		ret = -ENOMEM;
 		goto free_soc;
+	}
 
 	soc_dev_attr->serial_number = kasprintf(GFP_KERNEL, "%016llX", soc_uid);
-	if (!soc_dev_attr->serial_number)
+	if (!soc_dev_attr->serial_number) {
+		ret = -ENOMEM;
 		goto free_rev;
+	}
 
 	soc_dev = soc_device_register(soc_dev_attr);
-	if (IS_ERR(soc_dev))
+	if (IS_ERR(soc_dev)) {
+		ret = PTR_ERR(soc_dev);
 		goto free_serial_number;
+	}
 
-	return soc_device_to_device(soc_dev);
+	return 0;
 
 free_serial_number:
 	kfree(soc_dev_attr->serial_number);
@@ -243,5 +249,6 @@ free_rev:
 	kfree(soc_dev_attr->revision);
 free_soc:
 	kfree(soc_dev_attr);
-	return NULL;
+	return ret;
 }
+device_initcall(imx_soc_device_init);