wifi_statistics: first unlink, then free structure

Otherwise bad memory is accessed.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
wifi_statistics: add detailed signal strength

output some more stuff to let userspace compute statistical value (e.g.
sttdev or rms, these are floats which we don't want to bother with in
kernelspace)

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
wifi_statistics: collect rx_bytes

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
wifi_statistics: add seqno diff statistics

This patch tracks sequence number differences - the differences
should stay at 1 if there is no packet loss. Unify the statistics
gathering in a function at the same time (also used for signal
strength).

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
wifi_statistics: track transmitter address instead of SA

we are not interested in every single LAN mac address when AP
sends, but we want to know that the AP itself is sending. Therefore
track the transmitter address instead of source address.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
wifi_statistics: add moving average

a little hack is needed to allow signed values.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
wifi_statistics: unify detail printing

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
wifi_statistics: track BSSID and STA type

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
wifi_statistics: track packet interval

this patch also moves some general code into station.c

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
wifi_statistics: add module parameter for interface name

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
wifi_statistics: pimp the README

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>