Refactor ewk_popup_picker

Refactor ewk_popup_picker

[Title] Refactor ewk_popup_picker
[Issue#] N/A
[Problem] elm_genlist_item_index_get is not good function because it is based on loop.
[Cause] N/A
[Solution] N/A

1. Removed duplicated function, menuItemDeactivated.
2. Rename menuItemActivated because it is not for activation.
3. Tried not to call elm_genlist_item_index_get.
4. Removed unnecessary macro in labelGet.
5. Deleted unselect callback when destroyed.
6. Reorder member of _Ewk_Popup_Picker.

Change-Id: I37b31f61d929ada9c5f9ad89f6476bf1414d0be1