p2p/discv5: minor code simplification (#18188)

* Update net.go

more simple

* Update net.go

p2p/discv5/net.go

@@ -567,12 +567,11 @@ loop:
 			net.ticketStore.searchLookupDone(res.target, res.nodes, func(n *Node, topic Topic) []byte {
 				if n.state != nil && n.state.canQuery {
 					return net.conn.send(n, topicQueryPacket, topicQuery{Topic: topic}) // TODO: set expiration
-				} else {
+				}
 				if n.state == unknown {
 					net.ping(n, n.addr())
 				}
 				return nil				
-				}
 			})
 
 		case <-statsDump.C: