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/link.go

@@ -422,13 +422,14 @@ out:
 
 			// TODO(roasbeef): remove all together
 			go func() {
-				if err := l.cfg.Peer.WipeChannel(l.channel); err != nil {
+				chanPoint := l.channel.ChannelPoint()
+				if err := l.cfg.Peer.WipeChannel(chanPoint); err != nil {
 					log.Errorf("unable to wipe channel %v", err)
 				}
 
 				// TODO(roasbeef): need to send HTLC outputs to nursery
 				// TODO(roasbeef): or let the arb sweep?
-				l.cfg.SettledContracts <- l.channel.ChannelPoint()
+				l.cfg.SettledContracts <- chanPoint
 			}()
 
 			break out