Convert CONFIG_MII et al to Kconfig

This converts the following to Kconfig:
   CONFIG_MII
   CONFIG_DRIVER_TI_EMAC

Signed-off-by: Adam Ford <aford173@gmail.com>
Acked-by: Jagan Teki <jagan@amarulasolutions.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/configs/spear320_usbtty_defconfig b/configs/spear320_usbtty_defconfig
index f99e54b..63253b1 100644
--- a/configs/spear320_usbtty_defconfig
+++ b/configs/spear320_usbtty_defconfig
@@ -23,7 +23,7 @@
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_MTD_DEVICE=y
 CONFIG_MTD_PARTITIONS=y
-CONFIG_NETDEVICES=y
 CONFIG_PHY_GIGE=y
 CONFIG_ETH_DESIGNWARE=y
+CONFIG_MII=y
 CONFIG_CONS_INDEX=0