This is easier to deal with if it uses the existing string handling,
since we will be able to use translations, etc. in the future.
Update it to use an ID instead of a string.
Signed-off-by: Simon Glass <sjg@chromium.org>
An expo is a way of presenting and collecting information from the
user. It consists of a collection of 'scenes' of which only one is
presented at a time. An expo is typically used to show a boot menu
and allow settings to be changed.
One created, the same expo can be automatically presented in graphical
form using a vidconsole, or in text form on a serial console.
Add an initial implementation of the expo itself. Supports for scenes
and objects is provided later.
Signed-off-by: Simon Glass <sjg@chromium.org>
