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/cobra5272_defconfig b/configs/cobra5272_defconfig
index 03ac4a1..fc295af 100644
--- a/configs/cobra5272_defconfig
+++ b/configs/cobra5272_defconfig
@@ -12,4 +12,5 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_PING=y
 CONFIG_MTD_NOR_FLASH=y
+CONFIG_MII=y
 CONFIG_BAUDRATE=19200