staging/wlan-ng: remove obsolete comments

prism2sta_probe_usb() and prism2sta_disconnect_usb() header comments are
erroneous and useless. Removed.

Signed-off-by: Denis Pithon <denis.pithon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>