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/novena_defconfig b/configs/novena_defconfig
index 7454b73..6a076f8 100644
--- a/configs/novena_defconfig
+++ b/configs/novena_defconfig
@@ -43,7 +43,7 @@
 CONFIG_PHYLIB=y
 CONFIG_PHY_MICREL=y
 CONFIG_PHY_MICREL_KSZ90X1=y
-CONFIG_NETDEVICES=y
+CONFIG_MII=y
 CONFIG_PCI=y
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y