[nrf noup] board: nordic: thingy53: Enable default images for sysbuild

Enables MCUboot, empty network core and network core updates by
default when building for the thingy53

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

boards/nordic/thingy53/Kconfig.sysbuild

@@ -1,5 +1,25 @@
 # Copyright (c) 2024 Nordic Semiconductor ASA
 # SPDX-License-Identifier: Apache-2.0
 
+if BOARD_THINGY53_NRF5340_CPUAPP || BOARD_THINGY53_NRF5340_CPUAPP_NS
+
+choice BOOTLOADER
+	default BOOTLOADER_MCUBOOT
+endchoice
+
+config SECURE_BOOT
+	default y
+
+config SECURE_BOOT_NETCORE
+	default y if SECURE_BOOT
+
+config NETCORE_APP_UPDATE
+	default y if SECURE_BOOT
+
+config NRF_DEFAULT_EMPTY
+	default y
+
+endif # BOARD_THINGY53_NRF5340_CPUAPP || BOARD_THINGY53_NRF5340_CPUAPP_NS
+
 config PM_EXTERNAL_FLASH_MCUBOOT_SECONDARY
 	default y if BOOTLOADER_MCUBOOT