new_variant: add support for Dedede

The Dedede baseboard has two reference boards, Waddledee and
Waddledoo. Both are supported as the reference for creating a new
variant.

BUG=b:157183582
TEST=Create a new variant of Waddledee named Acro by following the
instructions in testdata/acro.md. After the build succeeds, clean up
as instructed.
Repeat the same procedure, except use --board=waddledoo instead of
--board=waddledee, to create Acro as a variant of Waddledoo. After
the build succeeds, clean up as instructed.
Either reference board works as a base for the new variant.

Change-Id: I88d20b9c47179914639b2dca22693336c4eccb7c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2212956
Tested-by: Paul Fagerburg <[email protected]>
Reviewed-by: Karthikeyan Ramasubramanian <[email protected]>
Commit-Queue: Paul Fagerburg <[email protected]>
4 files changed