If an iwi device is interrupted while scanning for an AP the scan lock
is not removed. Drivers for if_iwn.c and if_wpi.c have accounted for
this in the same manner. I believe if_ipw.c suffers from the same
problem, but I don't have a machine to verify it.

This diff is for 4.8-stable, but the issue is still in -current. I am
running it now, and things seem much more pleasant.

Thanks!

Index: if_iwi.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/if_iwi.c,v
retrieving revision 1.105
diff -r1.105 if_iwi.c
2350a2351,2353
quoted text
>       /* In case we were scanning, release the scan "lock". */
>       ic->ic_scan_lock = IEEE80211_SCAN_UNLOCKED;