fix: topicscore params can't be set for dynamically subscribed topic (l…

…ibp2p#540)

* fix: topicscore params can't be set for a topic subscribed after gossipsub is initialized

* chore:address review comments

score.go

@@ -202,13 +202,9 @@ func (ps *peerScore) SetTopicScoreParams(topic string, p *TopicScoreParams) erro
 	ps.Lock()
 	defer ps.Unlock()
 
-	old, exist := ps.params.Topics[topic]
+	old := ps.params.Topics[topic]
 	ps.params.Topics[topic] = p
 
-	if !exist {
-		return nil
-	}
-
 	// check to see if the counter Caps are being lowered; if that's the case we need to recap them
 	recap := false
 	if p.FirstMessageDeliveriesCap < old.FirstMessageDeliveriesCap {