DDN field isn't required, no point in writing an empty string to it. Change-Id: Ifea6e48c324598f114178e86a79f519ee35f5258 Signed-off-by: Matt DeVillier <matt.devillier@puri.sm> Reviewed-on: https://review.coreboot.org/c/coreboot/+/47781 Reviewed-by: Furquan Shaikh <furquan@google.com> Reviewed-by: Angel Pons <th3fanbus@gmail.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>