x86: kconfig: Let board select BOARD_EARLY_INIT_F

CONFIG_BOARD_EARLY_INIT_F literally indicates board-specific codes
and should be not 'default y' for all x86 boards.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/board/advantech/som-db5800-som-6867/Kconfig b/board/advantech/som-db5800-som-6867/Kconfig
index f6f3748..945aa43 100644
--- a/board/advantech/som-db5800-som-6867/Kconfig
+++ b/board/advantech/som-db5800-som-6867/Kconfig
@@ -21,6 +21,7 @@
 	select X86_RESET_VECTOR if !EFI_STUB
 	select INTEL_BAYTRAIL
 	select BOARD_ROMSIZE_KB_8192
+	select BOARD_EARLY_INIT_F
 
 config PCIE_ECAM_BASE
 	default 0xe0000000