futility: update the vbutil_kernel implementation

Now that the underlying bug is fixed (commit 64ef69c), this
replaces the old vbutil_kernel command implementation with the
new one that we rolled back in commit f1dba02.

BUG=chromium:418647
BRANCH=none
TEST=make runtests

I've also built an image with this change, installed it on a
Chromebook, ran make_dev_ssd.sh, make_dev_firmware.sh, recovered,
etc. Everything still works.

Change-Id: I8996e674a24b5d994658a6be2973ef3623cd659b
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/235429
Reviewed-by: Randall Spangler <rspangler@chromium.org>
3 files changed