ecore_event: Fix a break of consistency of return data

ecore_event: Fix a break of consistency of return data

Summary:
This patch fixes a break of consistency of return data from ecore_event_del.
Before EFL 1.20, when calling ecore_event_add(ECORE_EVENT_SIGNAL_USER, event_data, NULL, &data);
The user data(data) is saved at event->data. and when user calls ecore_event_del(event_handler),
ecore_event_del returns event->data. However, current ecore_event_del returns pd->ev.
I think it is ABI break.

Test Plan: Execute test suite

Reviewers: cedric, raster, stefan_schmidt, Jaehyun_Cho

Reviewed By: Jaehyun_Cho

Differential Revision: https://phab.enlightenment.org/D5786

Change-Id: Id0ff5dc61cbb18b0ffae378dd7490d4b75e0ed9f