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/UCP1020_SPIFLASH_defconfig b/configs/UCP1020_SPIFLASH_defconfig
index 952c0c6..fe3d046 100644
--- a/configs/UCP1020_SPIFLASH_defconfig
+++ b/configs/UCP1020_SPIFLASH_defconfig
@@ -6,6 +6,7 @@
 CONFIG_FIT_VERBOSE=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
+CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_HUSH_PARSER=y
 CONFIG_AUTOBOOT_KEYED=y
 CONFIG_AUTOBOOT_PROMPT="Autobooting in %d seconds, press \"<Esc>\" to stop\n"