HID: roccat: Fix NULL pointer dereference when unloading module

Class was destroyed before starting the unregistering driver chain.
Disconnecting a device from roccat chardev in this process then
raised a NULL pointer dereference.
Fixed this by destroying class after unregistering driver.

Signed-off-by: Stefan Achatz <erazor_de@users.sourceforge.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-roccat-kone.c b/drivers/hid/hid-roccat-kone.c
index 5cdb282..d749796 100644
--- a/drivers/hid/hid-roccat-kone.c
+++ b/drivers/hid/hid-roccat-kone.c
@@ -844,8 +844,8 @@
 
 static void __exit kone_exit(void)
 {
-	class_destroy(kone_class);
 	hid_unregister_driver(&kone_driver);
+	class_destroy(kone_class);
 }
 
 module_init(kone_init);