iwlwifi: mvm: enable pre-scan passive to active

Enable passive to active scan feature, on channels that was
active in the past hour.

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