config: add firmware configuration field

Based on go/fw-sku-and-hw-features, add a firmware configuration field
that each leave node of star config will fill out appropriately.

BRANCH=none
BUG=b:145519081
TEST=./generate and check output

Change-Id: I5b6049699538616c209af340180f6210e7d02966
Signed-off-by: Jett Rink <jettrink@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/1899345
Reviewed-by: Ned Nguyen <nednguyen@google.com>
3 files changed