Currently, vhost user nic doesn't support non msi guests(like pxe stage) by default.
Vhost user nic can't fall back to qemu like normal vhost net nic does. So we should
enable it for non msi guests.
Signed-off-by: NHaifeng Gao <gaohaifeng.gao@huawei.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>