mac80211: fix hardware scan completion

The mac80211 MLME requires restarting timers after a scan
completes but this wasn't done when hardware scan offload
was added, so add it now.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Tested-by: Bill Moss <bmoss@clemson.edu>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>