For historical reasons, no license information was added to the
tcl files. This makes trivial adding the SPDX tag through script:
fgrep -rL SPDX tcl/board | while read a;do \
sed -i '1{i# SPDX-License-Identifier: GPL-2.0-or-later\n
}' $a;done
With no specific license information from the author, let's extend
the OpenOCD project license GPL-2.0-or-later to the files.