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>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index cd9a820..811e558 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -913,6 +913,8 @@
 	imx8mm-venice-gw7902.dtb \
 	imx8mm-verdin.dtb \
 	phycore-imx8mm.dtb \
+	imx8mn-bsh-smm-s2.dtb \
+	imx8mn-bsh-smm-s2pro.dtb \
 	imx8mn-ddr4-evk.dtb \
 	imx8mq-cm.dtb \
 	imx8mn-evk.dtb \