funding: remove old TODO

fundingmanager.go

@@ -942,7 +942,6 @@ func (f *fundingManager) handleFundingOpen(fmsg *fundingOpenMsg) {
 		return
 	}
 
-	// TODO(roasbeef): error if funding flow already ongoing
 	fndgLog.Infof("Recv'd fundingRequest(amt=%v, push=%v, delay=%v, "+
 		"pendingId=%x) from peer(%x)", amt, msg.PushAmount,
 		msg.CsvDelay, msg.PendingChannelID,