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/SBx81LIFKW_defconfig b/configs/SBx81LIFKW_defconfig
index c786120..253f7f1 100644
--- a/configs/SBx81LIFKW_defconfig
+++ b/configs/SBx81LIFKW_defconfig
@@ -35,6 +35,7 @@
 CONFIG_MV88E61XX_CPU_PORT=10
 CONFIG_MV88E61XX_PHY_PORTS=0x003
 CONFIG_MV88E61XX_FIXED_PORTS=0x300
+CONFIG_MII=y
 CONFIG_DM_RTC=y
 CONFIG_RTC_MV=y
 CONFIG_SPI=y