SPL: Let spl_parse_image_header() return value

Allow the spl_parse_image_header() to return value. This is convenient
for controlling the SPL boot flow if the loaded image is corrupted.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Peng Fan <van.freenix@gmail.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Tom Rini <trini@konsulko.com>
diff --git a/common/spl/spl_nand.c b/common/spl/spl_nand.c
index 79388ff..bbd9546 100644
--- a/common/spl/spl_nand.c
+++ b/common/spl/spl_nand.c
@@ -32,7 +32,10 @@
 	if (err)
 		return err;
 
-	spl_parse_image_header(header);
+	err = spl_parse_image_header(header);
+	if (err)
+		return err;
+
 	return nand_spl_load_image(offset, spl_image.size,
 				   (void *)(unsigned long)spl_image.load_addr);
 }
@@ -77,7 +80,9 @@
 		/* load linux */
 		nand_spl_load_image(CONFIG_SYS_NAND_SPL_KERNEL_OFFS,
 			sizeof(*header), (void *)header);
-		spl_parse_image_header(header);
+		err = spl_parse_image_header(header);
+		if (err)
+			return err;
 		if (header->ih_os == IH_OS_LINUX) {
 			/* happy - was a linux */
 			err = nand_spl_load_image(