[nrf fromlist] boards: nrf54h20dk: Limit app core FLASH_LOAD_SIZE

Upstream PR #: 91413

CONFIG_USE_DT_CODE_PARTITION had to be disabled to add MCUboot support.
As a result, CONFIG_FLASH_LOAD_SIZE was left at zero, which means that
the linker would claim all available MRAM for the app core.

For now, we can't allow that, because the default nRF54H20 DK memory map
divides MRAM between multiple cores in order to support various samples.

Signed-off-by: Grzegorz Swiderski <[email protected]>
(cherry picked from commit d4ea476)

Author: 57300

boards/nordic/nrf54h20dk/Kconfig.defconfig

@@ -19,6 +19,11 @@ if !USE_DT_CODE_PARTITION
 config FLASH_LOAD_OFFSET
 	default $(dt_nodelabel_reg_addr_hex,cpuapp_boot_partition)
 
+# This is meant to span 'cpuapp_boot_partition' and 'cpuapp_slot0_partition'
+# in the default memory map.
+config FLASH_LOAD_SIZE
+	default 0x64000
+
 endif # !USE_DT_CODE_PARTITION
 
 endif # BOARD_NRF54H20DK_NRF54H20_CPUAPP

boards/nordic/nrf54h20dk/nrf54h20dk_nrf54h20_cpuapp_0_9_0.yaml

@@ -10,7 +10,7 @@ toolchain:
   - zephyr
 sysbuild: true
 ram: 256
-flash: 296
+flash: 400
 supported:
   - adc
   - can