doc: Fix function membership

Put the various misplaced functions in the right class; partly because
its where they belong, and partly to make intra-class \ref(erences)
happy.

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Derek Foreman <derekf@osg.samsung.com>