Disable EC jump after RW image starts

TEST=Built and booted Peppy. Ran flashrom from user space and
verified the EC firmware was updated after reboot.

CQ-DEPEND=CL:172651, CL:172652, CL:178324
BRANCH=none
BUG=chromium:325286
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Change-Id: Ia73da70dbf3abb5ced48666e86715c8d24a431a0
Reviewed-on: https://chromium-review.googlesource.com/172635
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@google.com>
Commit-Queue: Daisuke Nojiri <dnojiri@google.com>
4 files changed