repeat scanning could cause disassoc

[mabbas <mabbas@linux.intel.com>]

Hi
If I keep repeating scanning for like 4 times in the raw, the mac80211 
can disassociated because No ProbeResp.
looking at the rx patch if we are scanning we wont pass 
ieee80211_rx_h_passive_scan which only will deliver
beacon and probe request, which what we want, except that we only update 
last_rx in the function
ieee80211_rx_h_sta_process which is two functions down rx handlers.
In iwlwifi we do perform hw scan, in this command if scan takes a long 
time, and we are associated, it will tunes to associated channel to
allow getting beacons for a period of time, then continue with scanning. 
we do receive beacons on the associated
channel but mac80211 never update last_rx causing the disassociation.
I wonder if we can move ieee80211_rx_h_sta_process before 
ieee80211_rx_h_passive_scan or at least the rx_last
update part.
Thanks
Mohamed