Driver support for the monitor mode support that will be available in the next
OLPC 'bleeding edge' Marvell firmware release (most likely, 5.110.16.p2).

To activate monitor mode,

echo mode > /sys/class/net/{ethX,mshX}/device/libertas_rtap

where mode is the hex mask that specifies which frames to sniff (in short, 0x1
for data, 0x2 for all management but beacons, 0x4 for beacons). Any non zero
mode will activate the monitor mode, inhibiting transmission in ethX and mshX
interfaces and routing all the incoming traffic to a new rtapX interface that
will output the packets in 802.11+radiotap headers format.
Signed-off-by: Luis Carlos Cobo <luisca@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>