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/zynq_zc770_xm012_defconfig b/configs/zynq_zc770_xm012_defconfig
index 275bb33..5dee08e 100644
--- a/configs/zynq_zc770_xm012_defconfig
+++ b/configs/zynq_zc770_xm012_defconfig
@@ -38,5 +38,6 @@
 CONFIG_PHY_MARVELL=y
 CONFIG_PHY_REALTEK=y
 CONFIG_PHY_XILINX=y
+CONFIG_MII=y
 CONFIG_ZYNQ_GEM=y
 CONFIG_ZYNQ_SERIAL=y