vhost: move features to core

virtio 1 and any layout are core features, move them
there. This fixes vhost test.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --cc drivers/vhost/net.c
Simple merge

diff --cc drivers/vhost/scsi.c
Simple merge

diff --cc drivers/vhost/test.c
Simple merge

diff --cc drivers/vhost/vhost.h
Simple merge