sfp: fix non-detection of PHY

The detection of a PHY changed in commit e98a3aabf8 ("mdio_bus: don't
return NULL from mdiobus_scan()") which now causes sfp to print an
error message.  Update for this change.

Fixes: 7397005545 ("sfp: add SFP module support")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/sfp.c

@@ -356,12 +356,12 @@ static void sfp_sm_probe_phy(struct sfp *sfp)
 	msleep(T_PHY_RESET_MS);
 
 	phy = mdiobus_scan(sfp->i2c_mii, SFP_PHY_ADDR);
-	if (IS_ERR(phy)) {
-		dev_err(sfp->dev, "mdiobus scan returned %ld\n", PTR_ERR(phy));
+	if (phy == ERR_PTR(-ENODEV)) {
+		dev_info(sfp->dev, "no PHY detected\n");
 		return;
 	}
-	if (!phy) {
-		dev_info(sfp->dev, "no PHY detected\n");
+	if (IS_ERR(phy)) {
+		dev_err(sfp->dev, "mdiobus scan returned %ld\n", PTR_ERR(phy));
 		return;
 	}