audit: WARN if audit_rule_change called illegally

Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 4a11697..4419d1f 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -1085,7 +1085,8 @@
 		audit_free_rule(entry);
 		break;
 	default:
-		return -EINVAL;
+		err = -EINVAL;
+		WARN_ON(1);
 	}
 
 	return err;