Define all screens in enum ScreenIndex and use them

This enum seems partially complete, and not used in vboot_reference.
Complete it and use it.

BUG=chrome-os-partner:13492
BRANCH=snow
TEST=manual
Build and boot through to recovery on snow. Run through the various
screens and check that they still appear correctly.

Change-Id: Ifca54d072457d9a0396a38026f44f8334efb9cf5
Reviewed-on: https://gerrit.chromium.org/gerrit/32628
Reviewed-by: Mike Truty <truty@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Commit-Ready: Simon Glass <sjg@chromium.org>
(cherry picked from commit 69f0d0bac943d36cbce9c1e5309c86c27ef6eff8)
Reviewed-on: https://gerrit.chromium.org/gerrit/32868
Reviewed-by: Katie Roberts-Hoffman <katierh@chromium.org>
Tested-by: Katie Roberts-Hoffman <katierh@chromium.org>
2 files changed