elm/list: use while() loop to iterate item list during smart delete

Summary:
using EINA_LIST_FREE here double deletes 2 list items on every iteration
due to recursive list removals, which prevents some items from being
deleted as expected

fix T7266

Reviewers: netstar

Reviewed By: netstar

Subscribers: netstar, cedric, reviewers, committers

Tags: efl: widgets

Maniphest Tasks: T7266

Differential Revision: https://phab.enlightenment.org/D6829