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/MPC8548CDS_legacy_defconfig b/configs/MPC8548CDS_legacy_defconfig
index 0aa112a..55799db 100644
--- a/configs/MPC8548CDS_legacy_defconfig
+++ b/configs/MPC8548CDS_legacy_defconfig
@@ -17,9 +17,9 @@
 # CONFIG_MMC is not set
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_PHY_MARVELL=y
-CONFIG_NETDEVICES=y
 CONFIG_PHY_GIGE=y
 CONFIG_E1000=y
+CONFIG_MII=y
 CONFIG_TSEC_ENET=y
 CONFIG_CONS_INDEX=2
 CONFIG_SYS_NS16550=y