chore: update to use Arm word across TF-A

Align entire TF-A to use Arm in copyright header.

Change-Id: Ief9992169efdab61d0da6bd8c5180de7a4bc2244
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/lib/libfdt/libfdt.mk b/lib/libfdt/libfdt.mk
index 1cbbd78..812057d 100644
--- a/lib/libfdt/libfdt.mk
+++ b/lib/libfdt/libfdt.mk
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2016, Arm Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #