e_fm: add missing EINA_UNUSED
e_fm: add missing EINA_UNUSED

tizenorg/platform.upstream.enlightenment,tizenorg/platform.upstream.enlightenment,FlorentRevest/Enlightenment,FlorentRevest/Enlightenment,FlorentRevest/Enlightenment,tasn/enlightenment,rvandegrift/e,tizenorg/platform.upstream.enlightenment,rvandegrift/e,tasn/enlightenment,rvandegrift/e,tasn/enlightenment