board: BuR: 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>
Reviewed-by:  Hannes Schmelzer <hannes.schmelzer@br-automation.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

board/BuR/common/common.c

@@ -259,7 +259,8 @@ static int load_devicetree(void)
 	}
 #ifdef CONFIG_NAND
 	dtbsize = 0x20000;
-	rc = nand_read_skip_bad(nand_info[0], 0x40000, (size_t *)&dtbsize,
+	rc = nand_read_skip_bad(get_nand_dev_by_index(0), 0x40000,
+				(size_t *)&dtbsize,
 				NULL, 0x20000, (u_char *)dtbaddr);
 #else
 	char *dtbname = getenv("dtb");