tools: imagetool: Fix error message when verify_header is undefined

Signed-off-by: Pali Rohár <pali@kernel.org>
diff --git a/tools/imagetool.c b/tools/imagetool.c
index f14ca2f..688169b 100644
--- a/tools/imagetool.c
+++ b/tools/imagetool.c
@@ -105,7 +105,7 @@
 		}
 
 	} else {
-		fprintf(stderr, "%s: print_header undefined for %s\n",
+		fprintf(stderr, "%s: verify_header undefined for %s\n",
 			params->cmdname, tparams->name);
 	}