cmd/utils: fix help template issue for subcommands (ethereum#16351)

Author: niuzhenguo

cmd/utils/flags.go

@@ -64,7 +64,7 @@ var (
 {{if .cmd.Description}}{{.cmd.Description}}
 {{end}}{{if .cmd.Subcommands}}
 SUBCOMMANDS:
-	{{range .cmd.Subcommands}}{{.cmd.Name}}{{with .cmd.ShortName}}, {{.cmd}}{{end}}{{ "\t" }}{{.cmd.Usage}}
+	{{range .cmd.Subcommands}}{{.Name}}{{with .ShortName}}, {{.}}{{end}}{{ "\t" }}{{.Usage}}
 	{{end}}{{end}}{{if .categorizedFlags}}
 {{range $idx, $categorized := .categorizedFlags}}{{$categorized.Name}} OPTIONS:
 {{range $categorized.Flags}}{{"\t"}}{{.}}