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_fat.c b/common/spl/spl_fat.c
index d761b26..338ea2f 100644
--- a/common/spl/spl_fat.c
+++ b/common/spl/spl_fat.c
@@ -57,7 +57,9 @@
 	if (err <= 0)
 		goto end;
 
-	spl_parse_image_header(header);
+	err = spl_parse_image_header(header);
+	if (err <= 0)
+		goto end;
 
 	err = file_fat_read(filename, (u8 *)spl_image.load_addr, 0);