net: remove unnecessary carrier status check

Since netif_carrier_on() will do nothing if device's carrier is already
on, so it's unnecessary to do carrier status check.

It's the same for netif_carrier_off().
Signed-off-by: Zhang Shengju <zhangshengju@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -7245,13 +7245,10 @@ void netif_stacked_transfer_operstate(const struct net_device *rootdev,
 	else
 		netif_dormant_off(dev);
 
-	if (netif_carrier_ok(rootdev)) {
-		if (!netif_carrier_ok(dev))
+	if (netif_carrier_ok(rootdev))
 		netif_carrier_on(dev);
-	} else {
-		if (netif_carrier_ok(dev))
+	else
 		netif_carrier_off(dev);
-	}
 }
 EXPORT_SYMBOL(netif_stacked_transfer_operstate);