net: phy: marvell: use phy_modify_changed() for marvell_set_polarity()

Rather than open-coding the phy_modify_changed() sequence, use this
helper in marvell_set_polarity().
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Marek Behún <kabel@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/marvell.c

@@ -367,39 +367,24 @@ static irqreturn_t marvell_handle_interrupt(struct phy_device *phydev)
 
 static int marvell_set_polarity(struct phy_device *phydev, int polarity)
 {
-	int reg;
-	int err;
-	int val;
-
-	/* get the current settings */
-	reg = phy_read(phydev, MII_M1011_PHY_SCR);
-	if (reg < 0)
-		return reg;
+	u16 val;
 
-	val = reg;
-	val &= ~MII_M1011_PHY_SCR_AUTO_CROSS;
 	switch (polarity) {
 	case ETH_TP_MDI:
-		val |= MII_M1011_PHY_SCR_MDI;
+		val = MII_M1011_PHY_SCR_MDI;
 		break;
 	case ETH_TP_MDI_X:
-		val |= MII_M1011_PHY_SCR_MDI_X;
+		val = MII_M1011_PHY_SCR_MDI_X;
 		break;
 	case ETH_TP_MDI_AUTO:
 	case ETH_TP_MDI_INVALID:
 	default:
-		val |= MII_M1011_PHY_SCR_AUTO_CROSS;
+		val = MII_M1011_PHY_SCR_AUTO_CROSS;
 		break;
 	}
 
-	if (val != reg) {
-		/* Set the new polarity value in the register */
-		err = phy_write(phydev, MII_M1011_PHY_SCR, val);
-		if (err)
-			return err;
-	}
-
-	return val != reg;
+	return phy_modify_changed(phydev, MII_M1011_PHY_SCR,
+				  MII_M1011_PHY_SCR_AUTO_CROSS, val);
 }
 
 static int marvell_config_aneg(struct phy_device *phydev)