iwlwifi: apply settings when finishing scan

Even is someone else complete scanning in mac80211, apply rxon and
tx power settings if gets scan complete notification from hardware.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi W Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>