hw/ppc/spapr: Allow "spapr-vlan" as NIC model name beside "ibmveth"

hw/ppc/spapr: Allow "spapr-vlan" as NIC model name beside "ibmveth"

With the new "--nic" command line parameter option, the "old" way of
specifying a NIC model via the nd_table[] is becoming more prominent
again. But for the pseries "spapr-vlan" device, there is a confusing
discrepancy between the model name that is used for "--device" (i.e.
"spapr-vlan") and the model name that has to be used for "--net nic"
or the new "--nic" parameter (i.e. "ibmveth"). Since "spapr-vlan" is
the "real" name of the device, let's allow "spapr-vlan" to be used
as model name for the nd_table[] entries, too.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>