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/gwventana_defconfig b/configs/gwventana_defconfig
index 0819a22..6cc5897 100644
--- a/configs/gwventana_defconfig
+++ b/configs/gwventana_defconfig
@@ -19,6 +19,7 @@
 CONFIG_BOOTDELAY=3
 # CONFIG_SYS_STDIO_DEREGISTER is not set
 # CONFIG_DISPLAY_BOARDINFO is not set
+CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_SPL=y
 CONFIG_SPL_STACK_R=y
 CONFIG_SPL_DMA_SUPPORT=y