ARM: dts: add Altesco I6P board

Altesco (Altus-Escon-Company BV) I6P is a part of the diagnostic system
for the vehicle inspection stations.

Co-developed-by: David Jander <david@protonic.nl>
Signed-off-by: David Jander <david@protonic.nl>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>