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_picozed_defconfig b/configs/zynq_picozed_defconfig
index 0136502..239e063 100644
--- a/configs/zynq_picozed_defconfig
+++ b/configs/zynq_picozed_defconfig
@@ -35,6 +35,7 @@
 CONFIG_PHY_MARVELL=y
 CONFIG_PHY_REALTEK=y
 CONFIG_PHY_XILINX=y
+CONFIG_MII=y
 CONFIG_ZYNQ_GEM=y
 CONFIG_ZYNQ_SERIAL=y
 CONFIG_USB=y