virtio-net: Fix vhost virtqueue notifiers for RSS

virtio_net_guest_notifier_pending() and virtio_net_guest_notifier_mask()
checked VIRTIO_NET_F_MQ to know there are multiple queues, but
VIRTIO_NET_F_RSS also enables multiple queues. Refer to n->multiqueue,
which is set to true either of VIRTIO_NET_F_MQ or VIRTIO_NET_F_RSS is
enabled.

Fixes: 68b0a63 ("virtio-net: align ctrl_vq index for non-mq guest for vhost_vdpa")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
(cherry picked from commit 1c188fc)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/net/virtio-net.c

@@ -3370,7 +3370,7 @@ static bool virtio_net_guest_notifier_pending(VirtIODevice *vdev, int idx)
     VirtIONet *n = VIRTIO_NET(vdev);
     NetClientState *nc;
     assert(n->vhost_started);
-    if (!virtio_vdev_has_feature(vdev, VIRTIO_NET_F_MQ) && idx == 2) {
+    if (!n->multiqueue && idx == 2) {
         /* Must guard against invalid features and bogus queue index
          * from being set by malicious guest, or penetrated through
          * buggy migration stream.
@@ -3402,7 +3402,7 @@ static void virtio_net_guest_notifier_mask(VirtIODevice *vdev, int idx,
     VirtIONet *n = VIRTIO_NET(vdev);
     NetClientState *nc;
     assert(n->vhost_started);
-    if (!virtio_vdev_has_feature(vdev, VIRTIO_NET_F_MQ) && idx == 2) {
+    if (!n->multiqueue && idx == 2) {
         /* Must guard against invalid features and bogus queue index
          * from being set by malicious guest, or penetrated through
          * buggy migration stream.