driver core: fix using 'ret' variable in unregister_dynamic_debug_module

The 'ret' variable is assigned, but not used in the return statement. Fix this.
Signed-off-by: NJohann Felix Soden <johfel@users.sourceforge.net>
Acked-by: NJason Baron <jbaron@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

lib/dynamic_printk.c

@@ -135,7 +135,7 @@ int unregister_dynamic_debug_module(char *mod_name)
 	nr_entries--;
 out:
 	up(&debug_list_mutex);
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(unregister_dynamic_debug_module);