i2c: Make i2c_unregister_device() NULL-aware

It's a common pattern to be NULL-aware when freeing resources.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/i2c-core-base.c

@@ -819,6 +819,8 @@ EXPORT_SYMBOL_GPL(i2c_new_device);
  */
 void i2c_unregister_device(struct i2c_client *client)
 {
+	if (!client)
+		return;
 	if (client->dev.of_node)
 		of_node_clear_flag(client->dev.of_node, OF_POPULATED);
 	if (ACPI_COMPANION(&client->dev))
@@ -1436,8 +1438,7 @@ static int __unregister_client(struct device *dev, void *dummy)
 static int __unregister_dummy(struct device *dev, void *dummy)
 {
 	struct i2c_client *client = i2c_verify_client(dev);
-	if (client)
-		i2c_unregister_device(client);
+	i2c_unregister_device(client);
 	return 0;
 }