net: phy: don't double-read link status register if link is up

The link status register latches link-down events. Therefore, if link
is reported as being up, there's no need for a second read.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy-c45.c

@@ -148,6 +148,8 @@ int genphy_c45_read_link(struct phy_device *phydev)
 			val = phy_read_mmd(phydev, devad, MDIO_STAT1);
 			if (val < 0)
 				return val;
+			else if (val & MDIO_STAT1_LSTATUS)
+				continue;
 		}
 
 		val = phy_read_mmd(phydev, devad, MDIO_STAT1);