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/ts4600_defconfig b/configs/ts4600_defconfig
index 40e20c4..680a13c 100644
--- a/configs/ts4600_defconfig
+++ b/configs/ts4600_defconfig
@@ -6,6 +6,7 @@
 CONFIG_SYS_EXTRA_OPTIONS="ENV_IS_IN_MMC"
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 # CONFIG_DISPLAY_CPUINFO is not set
+CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_BOOTZ=y