No need to expose the way DRCs are traversed outside of spapr_drc.c.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20201218103400.689660-4-groug@kaod.org>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Tested-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>