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/doxygen/input/doc_hashing.h b/doxygen/input/doc_hashing.h
index 83613bf..931e6e9 100644
--- a/doxygen/input/doc_hashing.h
+++ b/doxygen/input/doc_hashing.h
@@ -6,7 +6,19 @@
 /*
  *
  *  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.
  */
 
 /**