Revert back to 2.28.5

git revert v2.28.5..v2.28.6
git rebase to combine the resulting revert commits

This reverts commit 3a91dad9dc.

scripts/generate_errors.pl

@@ -6,7 +6,19 @@
 # or generate_errors.pl include_dir data_dir error_file
 #
 # Copyright The Mbed TLS Contributors
-# SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
 use strict;
 use warnings;