dsa: lan9303: Add exception logic for read failure

While it is highly unlikely a read will ever fail, This code fragment is
now in a function that allows us to return an error code. A read failure
here will cause the lan9303_probe to fail.
Signed-off-by: Jerry Ray <jerry.ray@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/lan9303-core.c

@@ -911,7 +911,9 @@ static int lan9303_setup(struct dsa_switch *ds)
 	}
 
 	/* Virtual Phy: Remove Turbo 200Mbit mode */
-	lan9303_read(chip->regmap, LAN9303_VIRT_SPECIAL_CTRL, &reg);
+	ret = lan9303_read(chip->regmap, LAN9303_VIRT_SPECIAL_CTRL, &reg);
+	if (ret)
+		return (ret);
 
 	reg &= ~LAN9303_VIRT_SPECIAL_TURBO;
 	regmap_write(chip->regmap, LAN9303_VIRT_SPECIAL_CTRL, reg);