cmd:spl:fix: Prevent from a build error on boards, which don't support FDT

Do not compile in FDT related code, when it is not supported.
Signed-off-by: NLukasz Majewski <l.majewski@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Acked-by: NStefano Babic <sbabic@denx.de>

common/cmd_spl.c

@@ -130,10 +130,12 @@ static int spl_export(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 		if (call_bootm(argc, argv, subcmd_list[(int)c->cmd]))
 			return -1;
 		switch ((int)c->cmd) {
+#ifdef CONFIG_OF_LIBFDT
 		case SPL_EXPORT_FDT:
 			printf("Argument image is now in RAM: 0x%p\n",
 				(void *)images.ft_addr);
 			break;
+#endif
 		case SPL_EXPORT_ATAGS:
 			printf("Argument image is now in RAM at: 0x%p\n",
 				(void *)gd->bd->bi_boot_params);