zephyr: tests/subsys/storage/flash_map failure on twr_ke18f

Describe the bug platform: twrke18f Location: tests/subsys/storage/flash_map

To Reproduce Steps to reproduce the behavior:

1. mkdir build; cd build
2. cmake -DBOARD=twr_ke18f …
3. make flash
4. See error

Expected behavior test pass

Impact flash usage

Logs and console output

    *** Booting Zephyr OS version 2.3.99  ***
    Running test suite test_flash_map
    ===================================================================
    START - test_flash_area_get_sectors
    
        Assertion failed at WEST_TOPDIR/zephyr/tests/subsys/storage/flash_map/src/main.c:96: test_flash_area_get_sectors: (rc == 0 is false)
    area not erased
     FAIL - test_flash_area_get_sectors
    ===================================================================
    Test suite test_flash_map failed.
    ===================================================================
    PROJECT EXECUTION FAILED

Environment (please complete the following information):

• OS: (e.g. Linux)
• Toolchain (e.g Zephyr SDK, …)
• Commit SHA: ab3e778f47d