ARM: dts: imx8mm: Add i.MX8M Mini Toradex Verdin based Menlo board

Add new board based on the Toradex Verdin iMX8M Mini SoM, the MX8Menlo.
The board is a compatible replacement for i.MX53 M53Menlo and features
USB, multiple UARTs, ethernet, LEDs, SD and eMMC.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Cc: Max Krummenacher <max.krummenacher@toradex.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>