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/ls1021aiot_sdcard_defconfig b/configs/ls1021aiot_sdcard_defconfig
index f72bd4e..09d6ab1 100644
--- a/configs/ls1021aiot_sdcard_defconfig
+++ b/configs/ls1021aiot_sdcard_defconfig
@@ -2,6 +2,7 @@
 CONFIG_TARGET_LS1021AIOT=y
 CONFIG_DEFAULT_DEVICE_TREE="ls1021a-iot-duart"
 CONFIG_SYS_EXTRA_OPTIONS="RAMBOOT_PBL,SPL_FSL_PBL,SD_BOOT,SD_BOOT_QSPI"
+CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL=y
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_USE_SECTOR=y
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0xe8