net: atheros: remove conversion to bool in atl1c_start_mac()

No need to convert '==' expression to bool. This fixes the following
coccicheck warning:

drivers/net/ethernet/atheros/atl1c/atl1c_main.c:1189:63-68: WARNING:
conversion to bool not needed here
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/atheros/atl1c/atl1c_main.c

@@ -1186,7 +1186,7 @@ static void atl1c_start_mac(struct atl1c_adapter *adapter)
 	struct atl1c_hw *hw = &adapter->hw;
 	u32 mac, txq, rxq;
 
-	hw->mac_duplex = adapter->link_duplex == FULL_DUPLEX ? true : false;
+	hw->mac_duplex = adapter->link_duplex == FULL_DUPLEX;
 	hw->mac_speed = adapter->link_speed == SPEED_1000 ?
 		atl1c_mac_speed_1000 : atl1c_mac_speed_10_100;