drivers: board: Make the board drivers available in SPL

Make the board driver available in the SPL too. The board driver is a way
to provide useful information about the board and that can be useful in
the SPL too.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/board/Kconfig b/drivers/board/Kconfig
index 2a3fc9c..254f657 100644
--- a/drivers/board/Kconfig
+++ b/drivers/board/Kconfig
@@ -8,6 +8,9 @@
 
 if BOARD
 
+config SPL_BOARD
+	depends on SPL_DM
+	bool "Enable board driver support in SPL"
 
 config BOARD_GAZERBEAM
 	bool "Enable board driver for the Gazerbeam board"