EC-EFS: Copy dev keys from platform/ec Currently, ec.bin generated by cros_sdk contains and is signed by the dev keys in the platform/ec/<board> directory. This patch copies these dev keys to vboot_reference. BUG=b:73249665 BRANCH=none TEST=make runtests Change-Id: Id2a0b16dc6d404a6bea902fd5a401d6fc7caa2bf Signed-off-by: Daisuke Nojiri <[email protected]> Reviewed-on: https://chromium-review.googlesource.com/940665 Reviewed-by: Wai-Hong Tam <[email protected]> (cherry picked from commit 6164b22471a2d0dc26d875bc78036adf5fe706c8) Reviewed-on: https://chromium-review.googlesource.com/946749