net: thunderx: Select CONFIG_MDIO_OCTEON for ThunderX NIC

The CONFIG_MDIO_OCTEON is required so that the ThunderX NIC driver can
talk to the PHY drivers.
Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cavium/Kconfig

@@ -37,6 +37,8 @@ config	THUNDER_NIC_BGX
 	tristate "Thunder MAC interface driver (BGX)"
 	depends on 64BIT
 	default ARCH_THUNDER
+	select PHYLIB
+	select MDIO_OCTEON
 	---help---
 	  This driver supports programming and controlling of MAC
 	  interface from NIC physical function driver.