event_data would be better named expanded_data, then we can widen its scope
to other places in cooker where we need to access an expanded data store.
We certainly don't want multiple expanded data stores.
(Bitbake rev: 1a3c1c9203e1a1452314954f1cfd771e5c1ce89b)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>