vdpa/vdpa_sim_net: Report max device capabilities

Configure max supported virtqueues features on the management device.
This info can be retrieved using:

$ vdpa mgmtdev show
vdpasim_net:
  supported_classes net
  max_supported_vqs 2
  dev_features MAC ANY_LAYOUT VERSION_1 ACCESS_PLATFORM
Signed-off-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20220105114646.577224-15-elic@nvidia.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

drivers/vdpa/vdpa_sim/vdpa_sim_net.c

@@ -192,6 +192,7 @@ static struct vdpa_mgmt_dev mgmt_dev = {
 	.config_attr_mask = (1 << VDPA_ATTR_DEV_NET_CFG_MACADDR |
 			     1 << VDPA_ATTR_DEV_NET_CFG_MTU),
 	.max_supported_vqs = VDPASIM_NET_VQ_NUM,
+	.supported_features = VDPASIM_NET_FEATURES,
 };
 
 static int __init vdpasim_net_init(void)