prototype: Rename board_design to design

Based on naming feedback.

BUG=None
TEST=None

Change-Id: I70de488b438774b2d9e0ab24a8a7d85a4c72c795
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2003636
Reviewed-by: C Shapiro <shapiroc@chromium.org>
Commit-Queue: C Shapiro <shapiroc@chromium.org>
Tested-by: C Shapiro <shapiroc@chromium.org>
Auto-Submit: C Shapiro <shapiroc@chromium.org>
12 files changed