image: Create a table of information for each category

image: Create a table of information for each category

Add a table that contains the category name, the number of items in each
category and a pointer to the table of items. This will allow us to use
generic code to deal with the categories.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>