ARM: dts: imx: Add support for Data Modul i.MX8M Plus eDM SBC

Add support for Data Modul i.MX8M Plus eDM SBC board. This is an
evaluation board for various custom display units. Currently
supported are serial console, ethernet, eMMC, SD, SPI NOR, USB.

Signed-off-by: Marek Vasut <marex@denx.de>