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/apx4devkit_defconfig b/configs/apx4devkit_defconfig
index 90422cd..352e0f2 100644
--- a/configs/apx4devkit_defconfig
+++ b/configs/apx4devkit_defconfig
@@ -32,6 +32,7 @@
 CONFIG_MMC_MXS=y
 CONFIG_NAND=y
 CONFIG_NAND_MXS=y
+CONFIG_MII=y
 CONFIG_CONS_INDEX=0
 CONFIG_USB=y
 CONFIG_USB_EHCI_HCD=y