staging: wlan-ng: fix line style warnings in p80211netdev.h

This patch fixes the following checkpatch.pl warning in p80211netdev.h:
WARNING: line over 80 characters

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>