tools: mkimage: Show where signatures/keys are written

At present mkimage displays the node information but it is not clear what
signing action was taken. Add a message that shows it. For now it only
supports showing a single signing action, since that is the common case.

Sample:

   Signature written to 'sha1-basic/test.fit',
       node '/configurations/conf-1/signature'
   Public key written to 'sha1-basic/sandbox-u-boot.dtb',
       node '/signature/key-dev'

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/fit_image.c b/tools/fit_image.c
index 0e31f7d..15f7c82 100644
--- a/tools/fit_image.c
+++ b/tools/fit_image.c
@@ -74,7 +74,8 @@
 						params->require_keys,
 						params->engine_id,
 						params->cmdname,
-						params->algo_name);
+						params->algo_name,
+						&params->summary);
 	}
 
 	if (dest_blob) {