net: phy: make mdio_bus_phy_suspend/resume as __maybe_unused

When CONFIG_PM_SLEEP is disabled, the compiler warns about unused
functions:

drivers/net/phy/phy_device.c:273:12: error: unused function 'mdio_bus_phy_suspend' [-Werror,-Wunused-function]
static int mdio_bus_phy_suspend(struct device *dev)
drivers/net/phy/phy_device.c:293:12: error: unused function 'mdio_bus_phy_resume' [-Werror,-Wunused-function]
static int mdio_bus_phy_resume(struct device *dev)

The logic is intentional, so just mark these two as __maybe_unused
and remove the incorrect #ifdef.

Fixes: 4c0d2e96 ("net: phy: consider that suspend2ram may cut off PHY power")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20210225145748.404410-1-arnd@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/phy_device.c

@@ -230,7 +230,6 @@ static struct phy_driver genphy_driver;
 static LIST_HEAD(phy_fixup_list);
 static DEFINE_MUTEX(phy_fixup_lock);
 
-#ifdef CONFIG_PM
 static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 {
 	struct device_driver *drv = phydev->mdio.dev.driver;
@@ -270,7 +269,7 @@ static bool mdio_bus_phy_may_suspend(struct phy_device *phydev)
 	return !phydev->suspended;
 }
 
-static int mdio_bus_phy_suspend(struct device *dev)
+static __maybe_unused int mdio_bus_phy_suspend(struct device *dev)
 {
 	struct phy_device *phydev = to_phy_device(dev);
 
@@ -290,7 +289,7 @@ static int mdio_bus_phy_suspend(struct device *dev)
 	return phy_suspend(phydev);
 }
 
-static int mdio_bus_phy_resume(struct device *dev)
+static __maybe_unused int mdio_bus_phy_resume(struct device *dev)
 {
 	struct phy_device *phydev = to_phy_device(dev);
 	int ret;
@@ -316,7 +315,6 @@ static int mdio_bus_phy_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(mdio_bus_phy_pm_ops, mdio_bus_phy_suspend,
 			 mdio_bus_phy_resume);
-#endif /* CONFIG_PM */
 
 /**
  * phy_register_fixup - creates a new phy_fixup and adds it to the list