ARM: dts: Add lid GPIO key device node for Peach boards

The Exynos5420 Peach Pit and Exynos5800 Peach Pi boards have both
a power and lid GPIO keys but only the former was defined in the
DTS. Add DTS snippets for the lid GPIO key too. These were taken
from the downstream ChromeOS 3.8 kernel tree.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Kukjin Kim <kgene@kernel.org>