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/ipam390_defconfig b/configs/ipam390_defconfig
index c969550..f131852 100644
--- a/configs/ipam390_defconfig
+++ b/configs/ipam390_defconfig
@@ -38,4 +38,5 @@
 # CONFIG_MMC is not set
 CONFIG_NAND=y
 CONFIG_NAND_DAVINCI=y
+CONFIG_DRIVER_TI_EMAC=y
 CONFIG_SYS_NS16550=y