numa: add check that board supports cpu_index to node mapping

Default node mapping initialization already checks that board
supports cpu_index to node mapping and refuses to start if
it's not supported. Do the same for explicitly provided
mapping "-numa node,cpus=..."

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Message-Id: <1494415802-227633-6-git-send-email-imammedo@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
