Pass the `peer_state` lock through to `update_maps_on_chan_removal`

Pass the `peer_state` lock through to `update_maps_on_chan_removal`

`update_maps_on_chan_removal` is used to perform `ChannelManager`
state updates when a channel is being removed, prior to dropping
the `peer_state` lock. In a future commit we'll use it to update
fields in the `per_peer_state`, but in order to do so we'll need to
have access to that state in the macro.

Here we get set up for this by passing the per-peer state to
`update_maps_on_chan_removal`, which is sadly a fairly large patch.