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/bg0900_defconfig b/configs/bg0900_defconfig
index b30da0c..6de8162 100644
--- a/configs/bg0900_defconfig
+++ b/configs/bg0900_defconfig
@@ -34,6 +34,7 @@
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_BAR=y
 CONFIG_SPI_FLASH_STMICRO=y
+CONFIG_MII=y
 CONFIG_CONS_INDEX=0
 CONFIG_SPI=y
 CONFIG_MXS_SPI=y