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/gwventana_gw5904_defconfig b/configs/gwventana_gw5904_defconfig
index 15633a4..f522ebe 100644
--- a/configs/gwventana_gw5904_defconfig
+++ b/configs/gwventana_gw5904_defconfig
@@ -65,8 +65,8 @@
 CONFIG_MV88E61XX_CPU_PORT=5
 CONFIG_MV88E61XX_PHY_PORTS=0xf
 CONFIG_MV88E61XX_FIXED_PORTS=0x0
-CONFIG_NETDEVICES=y
 CONFIG_E1000=y
+CONFIG_MII=y
 CONFIG_PCI=y
 CONFIG_DM_SERIAL=y
 CONFIG_USB=y