ARM: imx: pico-imx8mq: Add support for Technexion Pico-iMX8MQ

Add initial support for Technexion Pico-iMX8MQ SoM on PicoPI carrier
board. Currently working is ethernet, serial, eMMC. DT is imported
from Linux 5.4.28 ("462afcd6e7ea") .

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: "NXP i.MX U-Boot Team" <uboot-imx@nxp.com>
Cc: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Stefano Babic <sbabic@denx.de>