powerpc/e8248e: Select PHYLIB only if NETDEVICES is enabled

Select PHYLIB only if NETDEVICES is enabled and MDIO_BITBANG only if
PHYLIB is present to avoid warnings from Kconfig.

To prevent undefined references during linking register MDIO driver only
if CONFIG_MDIO_BITBANG is enabled.
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Scott Wood <oss@buserror.net>

arch/powerpc/platforms/82xx/Kconfig

@@ -30,8 +30,8 @@ config EP8248E
 	select 8272
 	select 8260
 	select FSL_SOC
-	select PHYLIB
-	select MDIO_BITBANG
+	select PHYLIB if NETDEVICES
+	select MDIO_BITBANG if PHYLIB
 	help
 	  This enables support for the Embedded Planet EP8248E board.
 

arch/powerpc/platforms/82xx/ep8248e.c

@@ -298,7 +298,9 @@ static const struct of_device_id of_bus_ids[] __initconst = {
 static int __init declare_of_platform_devices(void)
 {
 	of_platform_bus_probe(NULL, of_bus_ids, NULL);
-	platform_driver_register(&ep8248e_mdio_driver);
+
+	if (IS_ENABLED(CONFIG_MDIO_BITBANG))
+		platform_driver_register(&ep8248e_mdio_driver);
 
 	return 0;
 }