ARM: dts: stm32: 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.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@st.com>