Enables the creation of a second interface prefixed 'rtap'.
This second interface will provide every received in radiotap
format.

This is useful for performing wireless network analysis while
maintaining an active association.

Example usage:

% modprobe ipw2200 rtap_iface=1
% ifconfig rtap0 up
% tethereal -i rtap0

If you do not specify 'rtap_iface=1' as a module parameter then
the rtap interface will not be created and you will need to turn
it on via sysfs:

% echo 1 > /sys/bus/pci/drivers/ipw2200/*/rtap_iface