net: phy: provide stub for fixed_phy_set_link_update

In preparation for updating the DSA code and avoid using ifdefs there,
provide an empty stub for fixed_phy_set_link_update when
CONFIG_FIXED_PHY is not selected.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/phy_fixed.h

@@ -18,6 +18,9 @@ extern int fixed_phy_register(unsigned int irq,
 			      struct fixed_phy_status *status,
 			      struct device_node *np);
 extern void fixed_phy_del(int phy_addr);
+extern int fixed_phy_set_link_update(struct phy_device *phydev,
+			int (*link_update)(struct net_device *,
+					   struct fixed_phy_status *));
 #else
 static inline int fixed_phy_add(unsigned int irq, int phy_id,
 				struct fixed_phy_status *status)
@@ -34,14 +37,12 @@ static inline int fixed_phy_del(int phy_addr)
 {
 	return -ENODEV;
 }
-#endif /* CONFIG_FIXED_PHY */
-
-/*
- * This function issued only by fixed_phy-aware drivers, no need
- * protect it with #ifdef
- */
-extern int fixed_phy_set_link_update(struct phy_device *phydev,
+static inline int fixed_phy_set_link_update(struct phy_device *phydev,
 			int (*link_update)(struct net_device *,
-					   struct fixed_phy_status *));
+					   struct fixed_phy_status *))
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_FIXED_PHY */
 
 #endif /* __PHY_FIXED_H */