vboot: Split ec software sync to its own file

This was previously done inside vboot_api_kernel.  But it has nothing to
do with kernel verification; that's just the only place where we could
easily put it given that vboot (currently) owns the firmware UI.

No outwardly-visible functionality changes.

BUG=chromium:611535
BRANCH=none
TEST=make runtests; emerge-kevin coreboot depthcharge

Change-Id: I8a434eb4449a5a86b129ecac61ad81d0ad55549c
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/404920
6 files changed