Convert CONFIG_BOARD_EARLY_INIT_F to Kconfig

This converts the following to Kconfig:
   CONFIG_BOARD_EARLY_INIT_F

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/liteboard_defconfig b/configs/liteboard_defconfig
index 11c5b35..f096471 100644
--- a/configs/liteboard_defconfig
+++ b/configs/liteboard_defconfig
@@ -10,6 +10,7 @@
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/imx-common/spl_sd.cfg"
 CONFIG_BOOTDELAY=1
 CONFIG_DEFAULT_FDT_FILE="imx6ul-liteboard.dtb"
+CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_BOOTZ=y