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/Marsboard_A10_defconfig b/configs/Marsboard_A10_defconfig
index b73c064..4226fde 100644
--- a/configs/Marsboard_A10_defconfig
+++ b/configs/Marsboard_A10_defconfig
@@ -10,6 +10,7 @@
 # CONFIG_SPL_DOS_PARTITION is not set
 # CONFIG_SPL_EFI_PARTITION is not set
 CONFIG_SCSI_AHCI=y
+CONFIG_MII=y
 CONFIG_SUN4I_EMAC=y
 CONFIG_SUNXI_NO_PMIC=y
 CONFIG_SCSI=y