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/M54455EVB_stm33_defconfig b/configs/M54455EVB_stm33_defconfig
index 28a2e48..62e9d26 100644
--- a/configs/M54455EVB_stm33_defconfig
+++ b/configs/M54455EVB_stm33_defconfig
@@ -28,5 +28,6 @@
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_STMICRO=y
+CONFIG_MII=y
 CONFIG_SPI=y
 CONFIG_CF_SPI=y