platform/x86: wmi: Cleanup exit routine in reverse order of init

The initialize routine is:
* class -> bus -> platform

The exit routine is:
* platform -> class -> bus

Fix the exit routine to be:
* platform -> bus -> class
Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

drivers/platform/x86/wmi.c

@@ -1264,8 +1264,8 @@ static int __init acpi_wmi_init(void)
 static void __exit acpi_wmi_exit(void)
 {
 	platform_driver_unregister(&acpi_wmi_driver);
-	class_unregister(&wmi_bus_class);
 	bus_unregister(&wmi_bus_type);
+	class_unregister(&wmi_bus_class);
 }
 
 subsys_initcall(acpi_wmi_init);