ACPI / fan: Make struct dev_pm_ops const

Silence the following checkpatch warning:
WARNING: struct dev_pm_ops should normally be const.

Signed-off-by: Kaiyen Chang <kaiyen.chang@intel.com>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/fan.c

@@ -46,7 +46,7 @@ MODULE_DEVICE_TABLE(acpi, fan_device_ids);
 #ifdef CONFIG_PM_SLEEP
 static int acpi_fan_suspend(struct device *dev);
 static int acpi_fan_resume(struct device *dev);
-static struct dev_pm_ops acpi_fan_pm = {
+static const struct dev_pm_ops acpi_fan_pm = {
 	.resume = acpi_fan_resume,
 	.freeze = acpi_fan_suspend,
 	.thaw = acpi_fan_resume,