MAINTAINERS: add virtio-vsock driver in the VIRTIO CORE section

MAINTAINERS: add virtio-vsock driver in the VIRTIO CORE section

The virtio-vsock driver is already under VM SOCKETS (AF_VSOCK),
managed pricipally with the net tree, and VIRTIO AND VHOST
VSOCK DRIVER. However, changes that only affect the virtio part
usually go with Michael's tree, so let's also put the driver in
the VIRTIO CORE section to have its maintainers in CC for changes
to the virtio-vsock driver.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20240829143757.85844-1-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>