net: make net sysfs attributes ro_after_init

The attributes of net devices are immutable.

Ideally, attribute groups would contain const attributes
but there are too many places that do modifications of list
during startup (in other code) to allow that.
Signed-off-by: NStephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/net-sysfs.c

@@ -508,7 +508,7 @@ static ssize_t phys_switch_id_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(phys_switch_id);
 
-static struct attribute *net_class_attrs[] = {
+static struct attribute *net_class_attrs[] __ro_after_init = {
 	&dev_attr_netdev_group.attr,
 	&dev_attr_type.attr,
 	&dev_attr_dev_id.attr,
@@ -597,7 +597,7 @@ NETSTAT_ENTRY(rx_compressed);
 NETSTAT_ENTRY(tx_compressed);
 NETSTAT_ENTRY(rx_nohandler);
 
-static struct attribute *netstat_attrs[] = {
+static struct attribute *netstat_attrs[] __ro_after_init = {
 	&dev_attr_rx_packets.attr,
 	&dev_attr_tx_packets.attr,
 	&dev_attr_rx_bytes.attr,