vboot: decouple EC/AUXFW sync from UI

Since we don't always want to show a UI on EC sync (for example, in
coreboot, where display hasn't been initialized), decouple
vb2api_ec_sync() from VbDisplayScreen() by leaving screen display out of
vboot and letting the caller (such as depthcharge) handle it. Similarly,
stop calling screen display function from vb2api_auxfw_sync().

In order to display screen from depthcharge, it needs to know the
locale. Therefore, add vb2api_get_locale() to vboot API, which returns
the locale from nvdata.

After this change, the constant EC_SLOW_UPDATE is no longer used, so
remove it from Makefile.

TEST=make runtests

Cq-Depend: chromium:2117776
Change-Id: I0e2e8ebdd26d48a2e94d36495c2e45a5734cdc5d
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2087016
Reviewed-by: Joel Kitching <kitching@chromium.org>
7 files changed