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/mx6sxsabreauto_defconfig b/configs/mx6sxsabreauto_defconfig
index 5cac856..359b9b6 100644
--- a/configs/mx6sxsabreauto_defconfig
+++ b/configs/mx6sxsabreauto_defconfig
@@ -40,6 +40,7 @@
 CONFIG_SPI_FLASH_BAR=y
 CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_PHYLIB=y
+CONFIG_MII=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX6=y
 CONFIG_DM_PMIC=y