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_zybo_z7_defconfig b/configs/zynq_zybo_z7_defconfig
index ad44e77..73930f1 100644
--- a/configs/zynq_zybo_z7_defconfig
+++ b/configs/zynq_zybo_z7_defconfig
@@ -50,6 +50,7 @@
 CONFIG_SPI_FLASH_BAR=y
 CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_PHY_REALTEK=y
+CONFIG_MII=y
 CONFIG_ZYNQ_GEM=y
 CONFIG_DEBUG_UART_ZYNQ=y
 CONFIG_ZYNQ_SERIAL=y