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/P2041RDB_defconfig b/configs/P2041RDB_defconfig
index 1149124..aea2574 100644
--- a/configs/P2041RDB_defconfig
+++ b/configs/P2041RDB_defconfig
@@ -6,6 +6,7 @@
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
 CONFIG_BOOTDELAY=10
+CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_GREPENV=y
 CONFIG_CMD_MMC=y