regulator: pca9450: Use devm_register_sys_off_handler

With module test, there is error dump:
------------[ cut here ]------------
  notifier callback pca9450_i2c_restart_handler already registered
  WARNING: kernel/notifier.c:23 at notifier_chain_register+0x5c/0x88,
  CPU#0: kworker/u16:3/50
  Call trace:
  notifier_chain_register+0x5c/0x88 (P)
  atomic_notifier_chain_register+0x30/0x58
  register_restart_handler+0x1c/0x28
  pca9450_i2c_probe+0x418/0x538
  i2c_device_probe+0x220/0x3d0
  really_probe+0x114/0x410
  __driver_probe_device+0xa0/0x150
  driver_probe_device+0x40/0x114
  __device_attach_driver+0xd4/0x12c

So use devm_register_sys_off_handler to let kernel handle the resource
free to avoid kernel dump.

Fixes: 6157e62 ("regulator: pca9450: Add restart handler")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://patch.msgid.link/20250815-pca9450-v1-1-7748e362dc97@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: MrVan

drivers/regulator/pca9450-regulator.c

@@ -40,7 +40,6 @@ struct pca9450 {
 	struct device *dev;
 	struct regmap *regmap;
 	struct gpio_desc *sd_vsel_gpio;
-	struct notifier_block restart_nb;
 	enum pca9450_chip_type type;
 	unsigned int rcnt;
 	int irq;
@@ -1100,10 +1099,9 @@ static irqreturn_t pca9450_irq_handler(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
-static int pca9450_i2c_restart_handler(struct notifier_block *nb,
-				unsigned long action, void *data)
+static int pca9450_i2c_restart_handler(struct sys_off_data *data)
 {
-	struct pca9450 *pca9450 = container_of(nb, struct pca9450, restart_nb);
+	struct pca9450 *pca9450 = data->cb_data;
 	struct i2c_client *i2c = container_of(pca9450->dev, struct i2c_client, dev);
 
 	dev_dbg(&i2c->dev, "Restarting device..\n");
@@ -1261,10 +1259,9 @@ static int pca9450_i2c_probe(struct i2c_client *i2c)
 	pca9450->sd_vsel_fixed_low =
 		of_property_read_bool(ldo5->dev.of_node, "nxp,sd-vsel-fixed-low");
 
-	pca9450->restart_nb.notifier_call = pca9450_i2c_restart_handler;
-	pca9450->restart_nb.priority = PCA9450_RESTART_HANDLER_PRIORITY;
-
-	if (register_restart_handler(&pca9450->restart_nb))
+	if (devm_register_sys_off_handler(&i2c->dev, SYS_OFF_MODE_RESTART,
+					  PCA9450_RESTART_HANDLER_PRIORITY,
+					  pca9450_i2c_restart_handler, pca9450))
 		dev_warn(&i2c->dev, "Failed to register restart handler\n");
 
 	dev_info(&i2c->dev, "%s probed.\n",