s390x/pci: rename hotplug handler callbacks

s390x/pci: rename hotplug handler callbacks

The callbacks are also called for cold plugged devices. Drop the "hot"
to better match the actual callback names.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Pierre Morel<pmorel@linux.ibm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>