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/kp_imx53_defconfig b/configs/kp_imx53_defconfig
index 47d17f9..d6f776c 100644
--- a/configs/kp_imx53_defconfig
+++ b/configs/kp_imx53_defconfig
@@ -34,6 +34,7 @@
 CONFIG_PHYLIB=y
 CONFIG_PHY_SMSC=y
 CONFIG_FEC_MXC=y
+CONFIG_MII=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX5=y
 # CONFIG_SPL_PMIC_CHILDREN is not set