mkimage: do not write incorrect error message

When running 'mkimage -l' is called for a valid StarFive file an error
message "Error: invalid marker bytes" is written by the Renesas SPKG
driver.

mkimage -l may be invoked without specifying an image type. In this case
mkimage iterates over all image type drivers to find the one that matches.
None of the non-matching drivers should write an error message.

Fix the Renesas SPKG driver.

Fixes: afdfcb11f97c ("tools: spkgimage: add Renesas SPKG format")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/renesas_spkgimage.c b/tools/renesas_spkgimage.c
index 5cd81dd..ce3b2b2 100644
--- a/tools/renesas_spkgimage.c
+++ b/tools/renesas_spkgimage.c
@@ -147,7 +147,8 @@
 
 	/* Check the marker bytes */
 	if (memcmp(header->marker, marker, 4)) {
-		fprintf(stderr, "Error: invalid marker bytes\n");
+		if (param->type == IH_TYPE_RENESAS_SPKG)
+			fprintf(stderr, "Error: invalid marker bytes\n");
 		return -EINVAL;
 	}