firmware: meson_sm: refactor serial sysfs entry via dev_groups attrs

Introduce just another way to register sysfs serial entry:
the less code, the better in the absence of extra error-paths

Signed-off-by: Evgeny Bachinin <EABachinin@salutedevices.com>
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20231108125604.162383-2-EABachinin@salutedevices.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>

Author: Evgeny Bachinin

drivers/firmware/meson/meson_sm.c

@@ -274,14 +274,11 @@ static ssize_t serial_show(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR_RO(serial);
 
-static struct attribute *meson_sm_sysfs_attributes[] = {
+static struct attribute *meson_sm_sysfs_attrs[] = {
 	&dev_attr_serial.attr,
 	NULL,
 };
-
-static const struct attribute_group meson_sm_sysfs_attr_group = {
-	.attrs = meson_sm_sysfs_attributes,
-};
+ATTRIBUTE_GROUPS(meson_sm_sysfs);
 
 static const struct of_device_id meson_sm_ids[] = {
 	{ .compatible = "amlogic,meson-gxbb-sm", .data = &gxbb_chip },
@@ -323,9 +320,6 @@ static int __init meson_sm_probe(struct platform_device *pdev)
 	if (devm_of_platform_populate(dev))
 		goto out_in_base;
 
-	if (sysfs_create_group(&pdev->dev.kobj, &meson_sm_sysfs_attr_group))
-		goto out_in_base;
-
 	pr_info("secure-monitor enabled\n");
 
 	return 0;
@@ -340,6 +334,7 @@ static struct platform_driver meson_sm_driver = {
 	.driver = {
 		.name = "meson-sm",
 		.of_match_table = of_match_ptr(meson_sm_ids),
+		.dev_groups = meson_sm_sysfs_groups,
 	},
 };
 module_platform_driver_probe(meson_sm_driver, meson_sm_probe);