Remove extra addition of dust due to excess counterparty htlc tx fees

In `can_accept_incoming_htlc`, `get_pending_htlc_stats`
accounts for the incoming htlc. Therefore,
`on_counterparty_tx_dust_exposure_msat` already includes
the excess tx fees of the incoming non-dust htlc.

Author: tankyleo

lightning/src/ln/channel.rs

@@ -7333,13 +7333,10 @@ impl<SP: Deref> FundedChannel<SP> where
 				return Err(("Exceeded our dust exposure limit on counterparty commitment tx", 0x1000|7))
 			}
 		} else {
-			let htlc_dust_exposure_msat =
-				per_outbound_htlc_counterparty_commit_tx_fee_msat(self.context.feerate_per_kw, &self.context.channel_type);
-			let counterparty_tx_dust_exposure =
-				htlc_stats.on_counterparty_tx_dust_exposure_msat.saturating_add(htlc_dust_exposure_msat);
-			if counterparty_tx_dust_exposure > max_dust_htlc_exposure_msat {
+			let on_counterparty_tx_dust_htlc_exposure_msat = htlc_stats.on_counterparty_tx_dust_exposure_msat;
+			if on_counterparty_tx_dust_htlc_exposure_msat > max_dust_htlc_exposure_msat {
 				log_info!(logger, "Cannot accept value that would put our exposure to tx fee dust at {} over the limit {} on counterparty commitment tx",
-					counterparty_tx_dust_exposure, max_dust_htlc_exposure_msat);
+					on_counterparty_tx_dust_htlc_exposure_msat, max_dust_htlc_exposure_msat);
 				return Err(("Exceeded our tx fee dust exposure limit on counterparty commitment tx", 0x1000|7))
 			}
 		}