fs: use get_nand_dev_by_index()

As part of preparation for nand DM conversion the new API has been
introduced to remove direct access to nand_info array. So, use it here
instead of accessing to nand_info array directly.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
diff --git a/fs/yaffs2/yaffs_uboot_glue.c b/fs/yaffs2/yaffs_uboot_glue.c
index f663081..bd66d316 100644
--- a/fs/yaffs2/yaffs_uboot_glue.c
+++ b/fs/yaffs2/yaffs_uboot_glue.c
@@ -166,11 +166,15 @@
 	char *mp = NULL;
 	struct nand_chip *chip;
 
+	mtd = get_nand_dev_by_index(flash_dev);
+	if (!mtd) {
+		error("\nno NAND devices available\n");
+		return;
+	}
+
 	dev = calloc(1, sizeof(*dev));
 	mp = strdup(_mp);
 
-	mtd = nand_info[flash_dev];
-
 	if (!dev || !mp) {
 		/* Alloc error */
 		printf("Failed to allocate memory\n");