USB: serial: visor: remove product and vendor module parameters

This driver is for devices that are no longer being made, so the ability
to add new device ids when loading the module is not a feature that
anyone uses anymore.  So remove it, which simplifies the startup code a
lot, and saves space.

If you still need to dynamically load device ids, that can be done
through sysfs.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>