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/at91rm9200ek_ram_defconfig b/configs/at91rm9200ek_ram_defconfig
index a7e630a..2688299 100644
--- a/configs/at91rm9200ek_ram_defconfig
+++ b/configs/at91rm9200ek_ram_defconfig
@@ -21,6 +21,7 @@
 CONFIG_ENV_IS_IN_FLASH=y
 # CONFIG_MMC is not set
 CONFIG_MTD_NOR_FLASH=y
+CONFIG_MII=y
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y
 CONFIG_USB_KEYBOARD=y