This API sets the attribute to show the input panel in case of only an user's explicit Mouse Up event.
It doesn't request to show the input panel even though it has focus.
feature did not build (missing the matching ecore_imf code) so I had
to revert it from EFL, which means this needs to be reverted also.
Revert "Add elm_entry_input_panel_show_on_demand_set/get()"
This reverts commit 3fc38ccc41d9b61efb4b5a8db08ea8290182bb7a.