MFC r216238:

MFC r216238:
Fix scanning after loosing a connection. The firmware assumes that as long
as an association ID is set any scan is supposed to be a background scan.
This implies that the firmware will switch back to the associated channel
after a certain threshold, though, we are not notified about that. We
currently catch this case by a timer which will reset the firmware after
a 'scan timeout', though, upper layers are not notified about that and
will simply hang until manual intervention. Fix this by resetting the
firmware's knowledge about any association on RUN -> ASSOC and
!INIT -> SCAN transitions.

Approved by:	re (kib)

git-svn-id: svn://svn.freebsd.org/base/stable/8@216411 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f