board: constify struct node_info array

Add 'const' (also 'static' in some places) to struct node_info
arrays to save memory footprint.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/board/toradex/colibri_imx7/colibri_imx7.c b/board/toradex/colibri_imx7/colibri_imx7.c
index f9f488d..2210095 100644
--- a/board/toradex/colibri_imx7/colibri_imx7.c
+++ b/board/toradex/colibri_imx7/colibri_imx7.c
@@ -389,7 +389,7 @@
 int ft_board_setup(void *blob, bd_t *bd)
 {
 #if defined(CONFIG_FDT_FIXUP_PARTITIONS)
-	static struct node_info nodes[] = {
+	static const struct node_info nodes[] = {
 		{ "fsl,imx7d-gpmi-nand", MTD_DEV_TYPE_NAND, }, /* NAND flash */
 		{ "fsl,imx6q-gpmi-nand", MTD_DEV_TYPE_NAND, },
 	};