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/at91rm9200ek_defconfig b/configs/at91rm9200ek_defconfig
index 9674a04..65ee8df 100644
--- a/configs/at91rm9200ek_defconfig
+++ b/configs/at91rm9200ek_defconfig
@@ -6,6 +6,7 @@
 # CONFIG_SYS_STDIO_DEREGISTER is not set
 # CONFIG_DISPLAY_CPUINFO is not set
 # CONFIG_DISPLAY_BOARDINFO is not set
+CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="U-Boot> "
 CONFIG_CMD_BOOTZ=y