Create bus_enumerate_hinted_children. This routine will allow drivers

Create bus_enumerate_hinted_children.  This routine will allow drivers
to use the hinted child system.  Bus drivers that use this need to
implmenet the bus_hinted_child method, where they actually add the
child to their bus, as they see fit.  The bus is repsonsible for
getting the attribtues for the child, adding it in the right order,
etc.  ISA hinting will be updated to use this method.

MFC After: 3 days