libiphone: fix -Werror=format-security compilation

Mandriva builds its packages with -Werror=format-security to make sure arguments to printf-like functions look sane. In particular, it will complain of constructs like printf(s) when s can't be resolved as a compile-time constant (which can be dangerous since 's' could contain printf formatters). There was a compile failure in libiphone/tools/ because of this flag, the attached patch fixes this.