iwlwifi: remove next_scan_jiffies

This logic is just confusing, if anything it
belongs into mac80211. Also, even if we do
scan during the EAPOL handshake, that will
not cause any problems, just a short delay.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>