bsh: imx8mn-smm-s2/pro: Add iMX8MN BSH SMM S2 boards

Introduce BSH SystemMaster (SMM) S2 board family, which consists of:
iMX8MN SMM S2 and iMX8MN SMM S2 PRO boards.

Add support for iMX8MN BSH SMM S2 board:

- 256 MiB DDR3 RAM
- 512MiB Nand
- USBOTG1 peripheral - fastboot.
- 100Mbit Ethernet

Add support for iMX8MN BSH SMM S2 PRO board:

- 512 MiB DDR3 RAM
- 8 GiB eMMC
- USBOTG1 peripheral - fastboot.
- 100Mbit Ethernet

Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
24 files changed