arm: imx8m: add support for Advantech RSB-3720

Add initial support for Advantech RSB-3720 board.
The initial support includes:
 - MMC
 - eMMC
 - I2C
 - FEC
 - Serial console

Signed-off-by: Darren Huang <darren.huang@advantech.com.tw>
Signed-off-by: Kevin12.Chen <Kevin12.Chen@advantech.com.tw>
Signed-off-by: Phill.Liu <Phill.Liu@advantech.com.tw>
Signed-off-by: Tim Liang <tim.liang@advantech.com.tw>
Signed-off-by: wei.zeng <wei.zeng@advantech.com.cn>
Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
Cc: uboot-imx <uboot-imx@nxp.com>
Cc: Peng Fan (OSS) <peng.fan@oss.nxp.com>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 5126ea8..3a811ae 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -1204,6 +1204,10 @@
 					imx8mm-cl-iot-gate-ied-tpm0.dtbo \
 					imx8mm-cl-iot-gate-ied-tpm1.dtbo
 
+ifneq ($(CONFIG_TARGET_IMX8MP_RSB3720A1_4G)$(CONFIG_TARGET_IMX8MP_RSB3720A1_6G),)
+dtb-y += imx8mp-rsb3720-a1.dtb
+endif
+
 dtb-$(CONFIG_TARGET_EA_LPC3250DEVKITV2) += lpc3250-ea3250.dtb
 
 dtb-$(CONFIG_ARCH_QEMU) += qemu-arm.dtb qemu-arm64.dtb