vhost: move vdpa group bound check to vhost_vdpa

vhost: move vdpa group bound check to vhost_vdpa

Remove duplication by consolidating these here.  This reduces the
posibility of a parent driver missing them.

While we're at it, fix a bug in vdpa_sim where a valid ASID can be
assigned to a group equal to ngroups, causing an out of bound write.

Cc: stable@vger.kernel.org
Fixes: bda324fd037a ("vdpasim: control virtqueue support")
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20260119143306.1818855-2-eperezma@redhat.com>