Common:fdt: Check for error return value

Check for negative return value of fdt_noffset from calling
boot_get_fdt_fit().

Signed-off-by: Hongwei Zhang <hongweiz@ami.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/common/image-fdt.c b/common/image-fdt.c
index 327a8c4..707b44a 100644
--- a/common/image-fdt.c
+++ b/common/image-fdt.c
@@ -407,6 +407,9 @@
 					&fit_uname_config,
 					arch, &load, &len);
 
+				if (fdt_noffset < 0)
+					goto error;
+
 				images->fit_hdr_fdt = map_sysmem(fdt_addr, 0);
 				images->fit_uname_fdt = fit_uname_fdt;
 				images->fit_noffset_fdt = fdt_noffset;