combobox: avoid calling item_selected and dismissed signal on show
combobox: avoid calling item_selected and dismissed signal on show

Summary:
After this patch https://phab.enlightenment.org/rELM0f6e1a46a402fd9cf848ffb1bd47c6b406eb7ffa
calling item,selected and dismissed signals should be avoided on combobox show.
Signed-off-by: Divyesh Purohit <purohit.div@gmail.com>

Test Plan: please run combobox example from elementary_test

Reviewers: cedric

Differential Revision: https://phab.enlightenment.org/D3603

Signed-off-by: Cedric BAIL <240633aa59d25638de9800ef43a88ad2e208d24d@osg.samsung.com>

tasn/elementary,rvandegrift/elementary,rvandegrift/elementary,rvandegrift/elementary,tasn/elementary,tasn/elementary,tasn/elementary,tasn/elementary,rvandegrift/elementary