USB: option: Added vendor id for Dell 5720 broadband modem

this is a small patch to add support for a rebranded Novatel modem (see
http://ubuntuforums.org/archive/index.php/t-608388.html for details).

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>