iwl3945: fix scan races

Port following patch to 3945.

"commit 90c4162ff59a3281b6d2f7206740be6217bd6758
Author: Johannes Berg <johannes.berg@intel.com>
Date:   Wed Apr 7 00:21:36 2010 -0700
    iwlwifi: fix scan races"

Signed-off-by: Abhijeet Kolekar <abhijeet.kolekar@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
index 867d105..04cedef 100644
--- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
+++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
@@ -3739,6 +3739,7 @@
 	INIT_DELAYED_WORK(&priv->_3945.rfkill_poll, iwl3945_rfkill_poll);
 	INIT_WORK(&priv->scan_completed, iwl_bg_scan_completed);
 	INIT_WORK(&priv->abort_scan, iwl_bg_abort_scan);
+	INIT_WORK(&priv->start_internal_scan, iwl_bg_start_internal_scan);
 	INIT_DELAYED_WORK(&priv->scan_check, iwl_bg_scan_check);
 
 	iwl3945_hw_setup_deferred_work(priv);
@@ -3761,6 +3762,7 @@
 	cancel_delayed_work_sync(&priv->init_alive_start);
 	cancel_delayed_work(&priv->scan_check);
 	cancel_delayed_work(&priv->alive_start);
+	cancel_work_sync(&priv->start_internal_scan);
 	cancel_work_sync(&priv->beacon_update);
 	if (priv->cfg->ops->lib->recover_from_tx_stall)
 		del_timer_sync(&priv->monitor_recover);