net: phy: make genphy_c45_write_eee_adv() static

genphy_c45_write_eee_adv() isn't used outside phy-c45.c,
so make it static.

Signed-off-by: Heiner Kallweit <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/phy/phy-c45.c

···
  * @phydev: target phy_device struct
  * @adv: the linkmode advertisement settings
  */
-int genphy_c45_write_eee_adv(struct phy_device *phydev, unsigned long *adv)
+static int genphy_c45_write_eee_adv(struct phy_device *phydev,
+				    unsigned long *adv)
 {
 	int val, changed = 0;
 

include/linux/phy.h

···
 			       struct ethtool_keee *data);
 int genphy_c45_ethtool_set_eee(struct phy_device *phydev,
 			       struct ethtool_keee *data);
-int genphy_c45_write_eee_adv(struct phy_device *phydev, unsigned long *adv);
 int genphy_c45_an_config_eee_aneg(struct phy_device *phydev);
 int genphy_c45_read_eee_adv(struct phy_device *phydev, unsigned long *adv);