tests: add copyright headers to all test files

They are missing and we need them if we want to opensource this.

Change-Id: I456ecd5ac5e33c7ada234f490389572d8932090b
Signed-off-by: Javi Merino <javi.merino@arm.com>
diff --git a/tests/test_plotter.py b/tests/test_plotter.py
index fa328b1..aaf4cda 100644
--- a/tests/test_plotter.py
+++ b/tests/test_plotter.py
@@ -1,4 +1,18 @@
 #!/usr/bin/env python
+# $Copyright:
+# ----------------------------------------------------------------
+# This confidential and proprietary software may be used only as
+# authorised by a licensing agreement from ARM Limited
+#  (C) COPYRIGHT 2015 ARM Limited
+#       ALL RIGHTS RESERVED
+# The entire notice above must be reproduced on all authorised
+# copies and copies may only be made to the extent permitted
+# by a licensing agreement from ARM Limited.
+# ----------------------------------------------------------------
+# File:        test_plotter.py
+# ----------------------------------------------------------------
+# $
+#
 
 import unittest
 import matplotlib