wlan0/iwn: no upload statistics

[Stefan Ehmann]

Network monitoring tools show download traffic, but no upload data.

systat -ifstat output:
Interface           Traffic               Peak                Total
     wlan0  in      1.066 KB/s         16.155 KB/s          377.757 MB
            out     0.000 KB/s          0.000 KB/s            0.000 KB


Tested on amd64 CURRENT from few days ago.

netword Card is:
iwn0: <Intel Centrino Ultimate-N 6300> mem 0xf2000000-0xf2001fff irq 17
at device 0.0 on pci3