spapr: Don't use spapr_drc_needed() in CAS code

spapr: Don't use spapr_drc_needed() in CAS code

We currently don't support hotplug of devices between boot and CAS. If
this happens a CAS reboot is triggered. We detect this during CAS using
the spapr_drc_needed() function which is essentially a VMStateDescription
.needed callback. Even if the condition for CAS reboot happens to be the
same as for DRC migration, it looks wrong to piggyback a migration helper
for this.

Introduce a helper with slightly more explicit name and use it in both CAS
and DRC migration code. Since a subsequent patch will enhance this helper
to cover the case of hot unplug, let's go for spapr_drc_transient(). While
here convert spapr_hotplugged_dev_before_cas() to the "transient" wording as
well.

This doesn't change any behaviour.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <158169248180.3465937.9531405453362718771.stgit@bahia.lan>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>