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/malta64_defconfig b/configs/malta64_defconfig
index 4308b4f..440a1b4 100644
--- a/configs/malta64_defconfig
+++ b/configs/malta64_defconfig
@@ -2,6 +2,7 @@
 CONFIG_TARGET_MALTA=y
 CONFIG_CPU_MIPS64_R2=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