USB: serial: option: add WeTelecom 0x6802 and 0x6803 products

These product IDs are listed in Windows driver.
0x6803 corresponds to WeTelecom WM-D300.
0x6802 name is unknown.

Signed-off-by: Aleksandr Makarov <aleksandr.o.makarov@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>