mac80211: dont set REQ_RUN when scan finishes

The timer restart is done wrongly, we shouldn't set the REQ_RUN
bit when the scan has finished if it hadn't been set before the
scan started. If the timer fires during the scan, it will set
REQ_RUN and then we can run the work for it, if it didn't fire
then we shouldn't run its work either.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>