[nrf fromlist] samples: Enable Direct XIP through sysbuild

Enable Direct XIP with revert MCUboot mode through sysbuild
configuration.

Upstream PR #: 95393

Signed-off-by: Tomasz Chyrowicz <[email protected]>

Author: tomchy

samples/subsys/mgmt/mcumgr/smp_svr/sample.yaml

@@ -103,6 +103,7 @@ tests:
     extra_args: EXTRA_CONF_FILE="overlay-serial.conf"
     extra_configs:
       - CONFIG_MCUBOOT_BOOTLOADER_MODE_DIRECT_XIP_WITH_REVERT=y
+      - SB_CONFIG_MCUBOOT_MODE_DIRECT_XIP_WITH_REVERT=y
     platform_allow:
       - nrf52840dk/nrf52840
       - pinnacle_100_dvk