leds: trigger: netdev: Use mutex instead of spinlocks

Some LEDs may require to sleep while doing some operation like setting
brightness and other cleanup.

For this reason, using a spinlock will cause a sleep under spinlock
warning.

It should be safe to convert this to a sleepable lock since:
- sysfs read/write can sleep
- netdev_trig_work is a work queue and can sleep
- netdev _trig_notify can sleep

The spinlock was used when brightness didn't support sleeping, but this
changed and now it supported with brightness_set_blocking().

Convert to mutex lock to permit sleeping using brightness_set_blocking().

Signed-off-by: Christian Marangi <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/leds/trigger/ledtrig-netdev.c

···
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/netdevice.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
 #include <linux/timer.h>
 #include "../leds.h"
 
···
  */
 
 struct led_netdev_data {
-	spinlock_t lock;
+	struct mutex lock;
 
 	struct delayed_work work;
 	struct notifier_block notifier;
···
 	struct led_netdev_data *trigger_data = led_trigger_get_drvdata(dev);
 	ssize_t len;
 
-	spin_lock_bh(&trigger_data->lock);
+	mutex_lock(&trigger_data->lock);
 	len = sprintf(buf, "%s\n", trigger_data->device_name);
-	spin_unlock_bh(&trigger_data->lock);
+	mutex_unlock(&trigger_data->lock);
 
 	return len;
 }
···
 
 	cancel_delayed_work_sync(&trigger_data->work);
 
-	spin_lock_bh(&trigger_data->lock);
+	mutex_lock(&trigger_data->lock);
 
 	if (trigger_data->net_dev) {
 		dev_put(trigger_data->net_dev);
···
 	trigger_data->last_activity = 0;
 
 	set_baseline_state(trigger_data);
-	spin_unlock_bh(&trigger_data->lock);
+	mutex_unlock(&trigger_data->lock);
 
 	return size;
 }
···
 
 	cancel_delayed_work_sync(&trigger_data->work);
 
-	spin_lock_bh(&trigger_data->lock);
+	mutex_lock(&trigger_data->lock);
 
 	trigger_data->carrier_link_up = false;
 	switch (evt) {
···
 
 	set_baseline_state(trigger_data);
 
-	spin_unlock_bh(&trigger_data->lock);
+	mutex_unlock(&trigger_data->lock);
 
 	return NOTIFY_DONE;
 }
···
 	if (!trigger_data)
 		return -ENOMEM;
 
-	spin_lock_init(&trigger_data->lock);
+	mutex_init(&trigger_data->lock);
 
 	trigger_data->notifier.notifier_call = netdev_trig_notify;
 	trigger_data->notifier.priority = 10;