vboot: Remove vb2_screen and vb2_ui_error enums
vboot: Remove vb2_screen and vb2_ui_error enums

Since all the functions that use these two enums are already removed,
these enums can be deleted as well.

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

Cq-Depend: chromium:3142709
Signed-off-by: edisonhello <faa7f329ec4feadaeda811ae464de0e9c3da9c05@google.com>
Change-Id: I1de42569e0f030b612ec3c6d00575a7efdcfdab9
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/3144447
Reviewed-by: Yu-Ping Wu <e17b963d2ce5bddd1fecae25c320252b132e804d@chromium.org>

coreboot/vboot,coreboot/vboot,coreboot/vboot,coreboot/vboot,coreboot/vboot