boards: siemens: iot2050: Unify PG1 and PG2/M.2 configurations again

This avoids having to maintain to defconfigs that are 99% equivalent.
The approach is to use binman to generate two flash images,
flash-pg1.bin and flash-pg2.bin. With the help of a template dtsi, we
can avoid duplicating the common binman image definitions.

Suggested-by: Andrew Davis <afd@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
diff --git a/board/siemens/iot2050/Kconfig b/board/siemens/iot2050/Kconfig
index e66b242..a6170aa 100644
--- a/board/siemens/iot2050/Kconfig
+++ b/board/siemens/iot2050/Kconfig
@@ -1,40 +1,22 @@
 # SPDX-License-Identifier: GPL-2.0+
 #
-# Copyright (c) Siemens AG, 2018-2022
+# Copyright (c) Siemens AG, 2018-2023
 #
 # Authors:
 #   Le Jin <le.jin@siemens.com>
 #   Jan Kiszka <jan.kiszka@siemens.com>
 
-choice
-        prompt "Siemens SIMATIC IOT2050 boards"
-        optional
-
-config TARGET_IOT2050_A53_PG1
-	bool "IOT2050 PG1 running on A53"
-	select IOT2050_A53_COMMON
-	help
-	  This builds U-Boot for the Product Generation 1 (PG1) of the IOT2050
-	  devices.
-
-config TARGET_IOT2050_A53_PG2
-	bool "IOT2050 PG2 running on A53"
-	select IOT2050_A53_COMMON
-	help
-	  This builds U-Boot for the Product Generation 2 (PG2) of the IOT2050
-	  devices.
-
-endchoice
-
-config IOT2050_A53_COMMON
-	bool
+config TARGET_IOT2050_A53
+	bool "IOT2050 running on A53"
 	select ARM64
 	select SOC_K3_AM654
 	select BOARD_LATE_INIT
 	select SYS_DISABLE_DCACHE_OPS
 	select BINMAN
+	help
+	  This builds U-Boot for the IOT2050 devices.
 
-if IOT2050_A53_COMMON
+if TARGET_IOT2050_A53
 
 config SYS_BOARD
 	default "iot2050"