arm: mach-k3: am65x: Move board selection to mach-k3

Currently each set of board targets from a vendor is selected inside
the board directory for that vendor. This has the problem of multiple
targets, one from each vendor, being selectable at the same time.
For instance you can select both TARGET_AM654_A53_EVM and
TARGET_IOT2050_A53 in the same build.

To fix this we need to move the target board choice to a common location
for each parent SoC selection. Do this in arch/arm/mach-k3.

Signed-off-by: Andrew Davis <afd@ti.com>
diff --git a/arch/arm/mach-k3/Kconfig b/arch/arm/mach-k3/Kconfig
index d5fdabe..01889e9 100644
--- a/arch/arm/mach-k3/Kconfig
+++ b/arch/arm/mach-k3/Kconfig
@@ -187,12 +187,11 @@
 	help
 	  SWRV for X509 certificate used for boot images
 
-source "board/ti/am65x/Kconfig"
+source "arch/arm/mach-k3/am65x/Kconfig"
 source "board/ti/am64x/Kconfig"
 source "board/ti/am62x/Kconfig"
 source "board/ti/am62ax/Kconfig"
 source "arch/arm/mach-k3/j721e/Kconfig"
-source "board/siemens/iot2050/Kconfig"
 source "board/ti/j721s2/Kconfig"
 source "board/toradex/verdin-am62/Kconfig"
 endif
diff --git a/arch/arm/mach-k3/am65x/Kconfig b/arch/arm/mach-k3/am65x/Kconfig
new file mode 100644
index 0000000..f17b641
--- /dev/null
+++ b/arch/arm/mach-k3/am65x/Kconfig
@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
+#	Andrew Davis <afd@ti.com>
+
+if SOC_K3_AM654
+
+choice
+	prompt "K3 AM65 based boards"
+	optional
+
+config TARGET_AM654_A53_EVM
+	bool "TI K3 based AM654 EVM running on A53"
+	select ARM64
+	select SYS_DISABLE_DCACHE_OPS
+	select BOARD_LATE_INIT
+	select BINMAN
+	imply TI_I2C_BOARD_DETECT
+
+config TARGET_AM654_R5_EVM
+	bool "TI K3 based AM654 EVM running on R5"
+	select CPU_V7R
+	select SYS_THUMB_BUILD
+	select K3_LOAD_SYSFW
+	select K3_AM654_DDRSS
+	select BINMAN
+	imply SYS_K3_SPL_ATF
+	imply TI_I2C_BOARD_DETECT
+
+config TARGET_IOT2050_A53
+	bool "IOT2050 running on A53"
+	depends on SOC_K3_AM654
+	select ARM64
+	select BOARD_LATE_INIT
+	select SYS_DISABLE_DCACHE_OPS
+	select BINMAN
+	help
+	  This builds U-Boot for the IOT2050 devices.
+
+endchoice
+
+source "board/ti/am65x/Kconfig"
+source "board/siemens/iot2050/Kconfig"
+
+endif
diff --git a/board/siemens/iot2050/Kconfig b/board/siemens/iot2050/Kconfig
index 737cda6..96dcfc4 100644
--- a/board/siemens/iot2050/Kconfig
+++ b/board/siemens/iot2050/Kconfig
@@ -6,16 +6,6 @@
 #   Le Jin <le.jin@siemens.com>
 #   Jan Kiszka <jan.kiszka@siemens.com>
 
-config TARGET_IOT2050_A53
-	bool "IOT2050 running on A53"
-	depends on SOC_K3_AM654
-	select ARM64
-	select BOARD_LATE_INIT
-	select SYS_DISABLE_DCACHE_OPS
-	select BINMAN
-	help
-	  This builds U-Boot for the IOT2050 devices.
-
 if TARGET_IOT2050_A53
 
 config SYS_BOARD
diff --git a/board/ti/am65x/Kconfig b/board/ti/am65x/Kconfig
index d5794b3..eb47a25 100644
--- a/board/ti/am65x/Kconfig
+++ b/board/ti/am65x/Kconfig
@@ -3,31 +3,6 @@
 # Copyright (C) 2017-2018 Texas Instruments Incorporated - https://www.ti.com/
 #	Lokesh Vutla <lokeshvutla@ti.com>
 
-choice
-	prompt "K3 AM65 based boards"
-	depends on SOC_K3_AM654
-	optional
-
-config TARGET_AM654_A53_EVM
-	bool "TI K3 based AM654 EVM running on A53"
-	select ARM64
-	select SYS_DISABLE_DCACHE_OPS
-	select BOARD_LATE_INIT
-	select BINMAN
-	imply TI_I2C_BOARD_DETECT
-
-config TARGET_AM654_R5_EVM
-	bool "TI K3 based AM654 EVM running on R5"
-	select CPU_V7R
-	select SYS_THUMB_BUILD
-	select K3_LOAD_SYSFW
-	select K3_AM654_DDRSS
-	select BINMAN
-	imply SYS_K3_SPL_ATF
-	imply TI_I2C_BOARD_DETECT
-
-endchoice
-
 if TARGET_AM654_A53_EVM
 
 config SYS_BOARD