master: disconnect only the phantom volume server

fix https://github.com/chrislusf/seaweedfs/issues/2311

weed/topology/data_node.go

@@ -18,6 +18,7 @@ type DataNode struct {
 	Port      int
 	PublicUrl string
 	LastSeen  int64 // unix time in seconds
+	Counter   int   // in race condition, the previous dataNode was not dead
 }
 
 func NewDataNode(id string) *DataNode {