r8169: add missing Kconfig dependency

Now that we switched the r8169 driver to use phylib, there's a
dependency on the Realtek PHY drivers. This dependency was missing
in Kconfig.
Reported-by: Jouni Mettälä <jtmettala@gmail.com>
Fixes: f1e911d5 ("r8169: add basic phylib support")
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/Kconfig

@@ -100,6 +100,7 @@ config R8169
 	select FW_LOADER
 	select CRC32
 	select PHYLIB
+	select REALTEK_PHY
 	---help---
 	  Say Y here if you have a Realtek 8169 PCI Gigabit Ethernet adapter.