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/mx53cx9020_defconfig b/configs/mx53cx9020_defconfig
index b1195c5..fec1eb4 100644
--- a/configs/mx53cx9020_defconfig
+++ b/configs/mx53cx9020_defconfig
@@ -25,8 +25,8 @@
 CONFIG_FPGA_ALTERA=y
 CONFIG_FPGA_CYCLON2=y
 CONFIG_FSL_ESDHC=y
-CONFIG_NETDEVICES=y
 CONFIG_FEC_MXC=y
+CONFIG_MII=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX5=y
 CONFIG_MXC_UART=y