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/A20-Olimex-SOM-EVB_defconfig b/configs/A20-Olimex-SOM-EVB_defconfig
index 92979a0..82fa109 100644
--- a/configs/A20-Olimex-SOM-EVB_defconfig
+++ b/configs/A20-Olimex-SOM-EVB_defconfig
@@ -21,6 +21,7 @@
 CONFIG_SCSI_AHCI=y
 CONFIG_ETH_DESIGNWARE=y
 CONFIG_RGMII=y
+CONFIG_MII=y
 CONFIG_SUN7I_GMAC=y
 CONFIG_AXP_ALDO3_VOLT=2800
 CONFIG_AXP_ALDO4_VOLT=2800