fix trace frame-queue unformat of index

Change-Id: Id891af5ef3c4afe877282b34cd03fc43886940a3
Signed-off-by: Matus Fabian <matfabia@cisco.com>
diff --git a/src/vlib/threads_cli.c b/src/vlib/threads_cli.c
index b64028c..54cc1ae 100644
--- a/src/vlib/threads_cli.c
+++ b/src/vlib/threads_cli.c
@@ -160,7 +160,7 @@
 	enable = 1;
       else if (unformat (line_input, "off"))
 	enable = 0;
-      else if (unformat (line_input, "index %u"), &index)
+      else if (unformat (line_input, "index %u", &index))
 	;
       else
 	return clib_error_return (0, "parse error: '%U'",