vboot: do not change screens when dev boot disallowed

In CL:2716747, VB2_SCREEN_DEVELOPER_TO_NORM is pulled up to act
as the root screen in the case of dev boot being disallowed.

As such, the screen changes can be removed from
VB2_SCREEN_DEVELOPER_MODE init() and reinit() functions.
If the user does manage to get into the developer mode screen
while developer mode is disabled, rely on the individual checks
in these functions to prevent booting:

- vb2_ui_developer_mode_boot_internal_action
- vb2_ui_developer_mode_boot_external_action
- vb2_ui_developer_mode_boot_altfw_action

BUG=b:159579189, b:181087237
TEST=make clean && make runtests
BRANCH=none

Signed-off-by: Joel Kitching <kitching@google.com>
Change-Id: Ic72d30709baeac2fc7e681d973413e2e9c8b0483
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2730669
Reviewed-by: Joel Kitching <kitching@chromium.org>
Tested-by: Joel Kitching <kitching@chromium.org>
Commit-Queue: Joel Kitching <kitching@chromium.org>
2 files changed