net: phy: c45: genphy_c45_an_config_aneg(): fix uninitialized symbol error

Fix warning:
drivers/net/phy/phy-c45.c:712 genphy_c45_write_eee_adv() error: uninitialized symbol 'changed'
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/r/202302150232.q6idsV8s-lkp@intel.com/
Fixes: 022c3f87 ("net: phy: add genphy_c45_ethtool_get/set_eee() support")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20230215050453.2251360-1-o.rempel@pengutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/phy-c45.c

@@ -256,7 +256,7 @@ static int genphy_c45_baset1_an_config_aneg(struct phy_device *phydev)
  */
 int genphy_c45_an_config_aneg(struct phy_device *phydev)
 {
-	int changed, ret;
+	int changed = 0, ret;
 	u32 adv;
 
 	linkmode_and(phydev->advertising, phydev->advertising,