ARM: dts: Add support for Liebherr's BK4 device (vf610 based)

This commit adds DTS support for BK4 device from Liebherr. It
uses vf610 SoC from NXP.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>