virtio-devices: vhost_user: Add VhostUserCommon::state() helper

With a common state structure for all vhost-user devices the state()
methods can also be refactored for reuse. This will make it easier to
add new common fields in the future for snapshot/restore.

Signed-off-by: Rob Bradford <rbradford@meta.com>

virtio-devices/src/vhost_user/net.rs

@@ -221,14 +221,7 @@ impl Net {
     }
 
     fn state(&self) -> State {
-        State {
-            avail_features: self.common.avail_features,
-            acked_features: self.common.acked_features,
-            config: self.config,
-            acked_protocol_features: self.vu_common.acked_protocol_features,
-            vu_num_queues: self.vu_common.vu_num_queues,
-            ..Default::default()
-        }
+        self.vu_common.state(&self.common, self.config)
     }
 }