iwlwifi: mvm: notify sched scan complete from stop routine

Add an option to notify mac80211 about sched scan complete from
iwl_mvm_stop_sched_scan(), to enable this notification when the
stop was called from within the driver.

Signed-off-by: David Spinadel <david.spinadel@intel.com>
Reviewed-by: Alexander Bondar <alexander.bondar@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>