Revert back to v3.5.0

git revert v3.5.0..v3.5.1
git rebase to combine the resulting revert commits

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/tests/scripts/check_files.py b/tests/scripts/check_files.py
index e359366..352b55e 100755
--- a/tests/scripts/check_files.py
+++ b/tests/scripts/check_files.py
@@ -1,7 +1,19 @@
 #!/usr/bin/env python3
 
 # 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.
 
 """
 This script checks the current state of the source code for minor issues,