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/flea3_defconfig b/configs/flea3_defconfig
index c7016b3..15e4596 100644
--- a/configs/flea3_defconfig
+++ b/configs/flea3_defconfig
@@ -29,6 +29,7 @@
 CONFIG_NAND_MXC=y
 CONFIG_PHYLIB=y
 CONFIG_PHY_MICREL=y
+CONFIG_MII=y
 CONFIG_SPI=y
 CONFIG_MXC_SPI=y
 CONFIG_OF_LIBFDT=y