cxgb3: fix mac index mapping

Override the mac index computation for the gen2 adapter,
as each port is expected to use index 0.
Signed-off-by: NDivy Le Ray <divy@chelsio.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/cxgb3/t3_hw.c

@@ -3682,6 +3682,8 @@ static void mc7_prep(struct adapter *adapter, struct mc7 *mc7,
 void mac_prep(struct cmac *mac, struct adapter *adapter, int index)
 {
 	mac->adapter = adapter;
+	if (!adapter->params.vpd.xauicfg[1])
+		index = 0;
 	mac->offset = (XGMAC0_1_BASE_ADDR - XGMAC0_0_BASE_ADDR) * index;
 	mac->nucast = 1;