Convert CONFIG_BOARD_TYPES to Kconfig

This converts the following to Kconfig:
   CONFIG_BOARD_TYPES

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/mscc_luton_defconfig b/configs/mscc_luton_defconfig
index 55edb19..d563901 100644
--- a/configs/mscc_luton_defconfig
+++ b/configs/mscc_luton_defconfig
@@ -21,6 +21,7 @@
 CONFIG_BOOTARGS="console=ttyS0,115200"
 CONFIG_LOGLEVEL=7
 CONFIG_DISPLAY_CPUINFO=y
+CONFIG_BOARD_TYPES=y
 CONFIG_BOARD_EARLY_INIT_R=y
 CONFIG_SYS_PROMPT="luton # "
 # CONFIG_CMD_BDI is not set