Fix unused import in benchmark builds

Author: TheBlueMatt

lightning/src/ln/channelmanager.rs

@@ -8781,7 +8781,7 @@ pub mod bench {
 	use crate::chain::Listen;
 	use crate::chain::chainmonitor::{ChainMonitor, Persist};
 	use crate::chain::keysinterface::{EntropySource, KeysManager, InMemorySigner};
-	use crate::ln::channelmanager::{self, BestBlock, ChainParameters, ChannelManager, PaymentHash, PaymentPreimage, PaymentId};
+	use crate::ln::channelmanager::{BestBlock, ChainParameters, ChannelManager, PaymentHash, PaymentPreimage, PaymentId};
 	use crate::ln::functional_test_utils::*;
 	use crate::ln::msgs::{ChannelMessageHandler, Init};
 	use crate::routing::gossip::NetworkGraph;