htlcswitch: update WipeChannel on Peer interface to simply take the chanPoint

The WipeChannel method doesn’t need to take the channel itself, as any
relevant indexes should be able to be queried based on the channel
point along.

htlcswitch/mock.go

@@ -332,7 +332,7 @@ func (s *mockServer) Disconnect(reason error) {
 	s.t.Fatalf("server %v was disconnected: %v", s.name, reason)
 }
 
-func (s *mockServer) WipeChannel(*lnwallet.LightningChannel) error {
+func (s *mockServer) WipeChannel(*wire.OutPoint) error {
 	return nil
 }