vboot: Remove vb2ex_display_ui, vb2ex_prepare_log_screen

After UI code is centralized, these functions are not used in vboot
anymore. Remove these two functions.

BUG=b:172339016
TEST=DEBUG=1 make -j test_setup && make -j runtests
BRANCH=none

Cq-Depend: chromium:3142705
Signed-off-by: edisonhello <edisonhello@google.com>
Change-Id: If773de4bbe835cb75f76c501429f305ef8d4fec4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/3144446
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
2 files changed