ARM: dts: exynos: Clarify comment explaining purpose of Odroid XU3 DTSI

There are two common DTSI files for Exynos5422 Odroid XU3 family of
boards.  One is shared between all of them (XU3, XU3-Lite, XU4 and HC1)
and the second skips HC1.  Document this in the files.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

arch/arm/boot/dts/exynos5422-odroid-core.dtsi

 // SPDX-License-Identifier: GPL-2.0
 /*
- * Hardkernel Odroid XU3/XU4/HC1 boards core device tree source
+ * Hardkernel Odroid XU3/XU3-Lite/XU4/HC1 boards core device tree source
  *
  * Copyright (c) 2017 Marek Szyprowski
  * Copyright (c) 2013-2017 Samsung Electronics Co., Ltd.

arch/arm/boot/dts/exynos5422-odroidxu3-common.dtsi

 // SPDX-License-Identifier: GPL-2.0
 /*
- * Hardkernel Odroid XU3 board device tree source
+ * Hardkernel Odroid XU3/XU3-Lite/XU4 boards common device tree source
  *
  * Copyright (c) 2013 Samsung Electronics Co., Ltd.
  *		http://www.samsung.com