efl_ui_focus_manager_sub: do not specify a interface as first argument

efl_ui_focus_manager_sub: do not specify a interface as first argument

this leads in eo to the meaning that the manager.sub is giving
implementations to that interface, but leaving the ->func with NULL,
which leads on some maschines to the assumation that this is
pure_virtual, which means not composition objects will be queried, on
other maschines this will work, since there other inherits will
overwrite this entry and set ->src to NULL.

While i still dont understand why this works on some maschines and does
not on others, this is is now fixed.