ARM: dts: imx6ull-dhcom: Add DHSOM based DRC02 board

Add DT for DH DRC02 unit, which is a universal controller device.
The system has two ethernet ports, two CANs, RS485 and RS232, USB,
capacitive buttons and an OLED display. For this board a DHCOM
i.MX6ULL SoM configuration without WiFi/BT is used. The interface
is used for the SD card instead.

Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>