pseries: Add cleanup hook for PAPR virtual LAN device

pseries: Add cleanup hook for PAPR virtual LAN device

Currently the spapr-vlan device does not supply a cleanup call for its
NetClientInfo structure.  With current qemu versions, that leads to a SEGV
on exit, when net_cleanup() attempts to call the cleanup handlers on all
net clients.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>
(cherry picked from commit 156dfaded87d718a9ea798083e1c3e5ea7526713)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>