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/B4860QDS_NAND_defconfig b/configs/B4860QDS_NAND_defconfig
index 802ac75a..0cd3223 100644
--- a/configs/B4860QDS_NAND_defconfig
+++ b/configs/B4860QDS_NAND_defconfig
@@ -40,9 +40,9 @@
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_SST=y
 CONFIG_PHYLIB=y
-CONFIG_NETDEVICES=y
 CONFIG_PHY_GIGE=y
 CONFIG_E1000=y
+CONFIG_MII=y
 CONFIG_SYS_NS16550=y
 CONFIG_SPI=y
 CONFIG_FSL_ESPI=y