board: siemens: Add support for SIMATIC IOT2050 devices

This adds support for the IOT2050 Basic and Advanced devices. The Basic
used the dual-core AM6528 GP processor, the Advanced one the AM6548 HS
quad-core version.

Both variants are booted via a Siemens-provided FSBL that runs on the R5
cores. Consequently, U-Boot support is targeting the A53 cores. U-Boot
SPL, ATF and TEE have to reside in SPI flash.

Full integration into a bootable image can be found on
https://github.com/siemens/meta-iot2050

Based on original board support by Le Jin, Gao Nian and Chao Zeng.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
diff --git a/board/siemens/iot2050/MAINTAINERS b/board/siemens/iot2050/MAINTAINERS
new file mode 100644
index 0000000..1b52535
--- /dev/null
+++ b/board/siemens/iot2050/MAINTAINERS
@@ -0,0 +1,9 @@
+IOT2050 BOARD
+M:	Le Jin <le.jin@siemens.com>
+M:	Jan Kiszka <jan.kiszka@siemens.com>
+S:	Maintained
+F:	board/siemens/iot2050/
+F:	include/configs/iot2050.h
+F:	configs/iot2050_defconfig
+F:	arch/arm/dts/iot2050-*
+F:	doc/board/siemens/iot2050.rst