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_net.c b/common/spl/spl_net.c
index 63b20d8..ae71d26 100644
--- a/common/spl/spl_net.c
+++ b/common/spl/spl_net.c
@@ -34,7 +34,5 @@
 		printf("Problem booting with BOOTP\n");
 		return rv;
 	}
-	spl_parse_image_header((struct image_header *)load_addr);
-
-	return 0;
+	return spl_parse_image_header((struct image_header *)load_addr);
 }