tools: update copyright header for commit log check

The commit log check script carried modifications made by Arm. Update
the copyright header in that script to acknowledge these modifications.

Fixes: 007645d3 ("scripts: resolve shell static analysis issues")
Fixes: 2329970d ("tools: verify correct commit tag order")
Signed-off-by: Nathan Brown <nathan.brown@arm.com>
Reviewed-by: Dhruv Tripathi <dhruv.tripathi@arm.com>

Change-Id: Iea4997e11a4eb8a79539cec0a12c61a912d8f173