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/malta_defconfig b/configs/malta_defconfig
index f1c8118..e848f42 100644
--- a/configs/malta_defconfig
+++ b/configs/malta_defconfig
@@ -1,6 +1,7 @@
 CONFIG_MIPS=y
 CONFIG_TARGET_MALTA=y
 CONFIG_DEFAULT_DEVICE_TREE="mti,malta"
+CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="malta # "
 # CONFIG_AUTOBOOT is not set