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/mx6sxsabresd_spl_defconfig b/configs/mx6sxsabresd_spl_defconfig
index 0e82bd7..5738113 100644
--- a/configs/mx6sxsabresd_spl_defconfig
+++ b/configs/mx6sxsabresd_spl_defconfig
@@ -48,6 +48,7 @@
 CONFIG_FSL_ESDHC=y
 CONFIG_SPI_FLASH=y
 CONFIG_PHYLIB=y
+CONFIG_MII=y
 CONFIG_PCI=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX6=y