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/xilinx_zynqmp_zc1751_xm018_dc4_defconfig b/configs/xilinx_zynqmp_zc1751_xm018_dc4_defconfig
index efb0b20..b1d8a24 100644
--- a/configs/xilinx_zynqmp_zc1751_xm018_dc4_defconfig
+++ b/configs/xilinx_zynqmp_zc1751_xm018_dc4_defconfig
@@ -62,6 +62,7 @@
 CONFIG_PHY_FIXED=y
 CONFIG_DM_ETH=y
 CONFIG_PHY_GIGE=y
+CONFIG_MII=y
 CONFIG_ZYNQ_GEM=y
 CONFIG_DEBUG_UART_ZYNQ=y
 CONFIG_DEBUG_UART_ANNOUNCE=y