boards: lpcxpresso55s69: BL2=OFF memory settings
boards: lpcxpresso55s69: BL2=OFF memory settings

Create a special configuration when BL2=OFF is set. DTS partitioning is
used for MCUboot, but does not match TFM's flash_layout.h configuration
when BL2=OFF, DTS matches when BL2=ON.

Signed-off-by: Andrei Gansari <f1330555a90b7a22d81843f3c4366f58b50eae34@nxp.com>

zephyrproject-rtos/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr,nashif/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,finikorg/zephyr,nashif/zephyr,Vudentz/zephyr