new_variant: add Dalboz as a valid reference board

The Zork baseboard has two reference boards, Trembyle (already
supported) and Dalboz. Add support for creating a variant of the
Dalboz reference board.

BUG=b:157099580
TEST=Create a new variant of Trembyle named Grue by following the
instructions in testdata/grue.md. After the build succeeds, clean up
as instructed.
Repeat the same procedure, except use --board=dalboz instead of
--board=trembyle, to create Grue as a variant of Dalboz. After the
build succeeds, clean up as instructed.
Either reference board works as a base for the new variant.

Cq-Depend: chromium:2209722
Change-Id: Iec59b8a162a4bbc54dbe82afd395380f5e20c278
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2209921
Tested-by: Paul Fagerburg <pfagerburg@chromium.org>
Commit-Queue: Paul Fagerburg <pfagerburg@chromium.org>
Reviewed-by: Raul E Rangel <rrangel@chromium.org>
4 files changed