staging: wlan-ng: use GENMASK macro in define of p80211netdev.h

This patch replace actual mask stuff using BIT macros with
or operators to make use of GENMASK macro which simplifies
code clearity and readibility.

It applies for defines included in p80211netdev.h header file.

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