net: phy: micrel: fix config_intr error handling

Make sure never to update the control register with random data (an
error code) by checking the return value after reading it.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/micrel.c

@@ -122,6 +122,8 @@ static int kszphy_config_intr(struct phy_device *phydev)
 
 	/* set the interrupt pin active low */
 	temp = phy_read(phydev, MII_KSZPHY_CTRL);
+	if (temp < 0)
+		return temp;
 	temp &= ~KSZPHY_CTRL_INT_ACTIVE_HIGH;
 	phy_write(phydev, MII_KSZPHY_CTRL, temp);
 	rc = kszphy_set_interrupt(phydev);
@@ -134,6 +136,8 @@ static int ksz9021_config_intr(struct phy_device *phydev)
 
 	/* set the interrupt pin active low */
 	temp = phy_read(phydev, MII_KSZPHY_CTRL);
+	if (temp < 0)
+		return temp;
 	temp &= ~KSZ9021_CTRL_INT_ACTIVE_HIGH;
 	phy_write(phydev, MII_KSZPHY_CTRL, temp);
 	rc = kszphy_set_interrupt(phydev);
@@ -146,6 +150,8 @@ static int ks8737_config_intr(struct phy_device *phydev)
 
 	/* set the interrupt pin active low */
 	temp = phy_read(phydev, MII_KSZPHY_CTRL);
+	if (temp < 0)
+		return temp;
 	temp &= ~KS8737_CTRL_INT_ACTIVE_HIGH;
 	phy_write(phydev, MII_KSZPHY_CTRL, temp);
 	rc = kszphy_set_interrupt(phydev);