platform/x86: wmi: Fix error handling in acpi_wmi_init()

The order of resource deallocations is messed up in acpi_wmi_init().
It should be vice versa.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

drivers/platform/x86/wmi.c

@@ -1252,12 +1252,12 @@ static int __init acpi_wmi_init(void)
 
 	return 0;
 
-err_unreg_class:
-	class_unregister(&wmi_bus_class);
-
 err_unreg_bus:
 	bus_unregister(&wmi_bus_type);
 
+err_unreg_class:
+	class_unregister(&wmi_bus_class);
+
 	return error;
 }