net: phy: fix sign type error in genphy_config_eee_advert

In genphy_config_eee_advert, the return value of phy_read_mmd_indirect is
checked to know if the register could be accessed but the result is
assigned to a 'u32'.
Changing to 'int' to correctly get errors from phy_read_mmd_indirect.

Fixes: d853d145 ("net: phy: add an option to disable EEE advertisement")
Reported-by: NJulia Lawall <julia.lawall@lip6.fr>
Signed-off-by: NJerome Brunet <jbrunet@baylibre.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/phy/phy_device.c

@@ -1187,8 +1187,8 @@ static int genphy_config_advert(struct phy_device *phydev)
  */
 static int genphy_config_eee_advert(struct phy_device *phydev)
 {
-	u32 broken = phydev->eee_broken_modes;
-	u32 old_adv, adv;
+	int broken = phydev->eee_broken_modes;
+	int old_adv, adv;
 
 	/* Nothing to disable */
 	if (!broken)