iwlagn: fix slot programming

When an AP mode interface is added with a DTIM
period of two, the slot programming is wrong.
Fix it by taking into account the DTIM period.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-agn-rxon.c

@@ -370,7 +370,7 @@ int iwlagn_set_pan_params(struct iwl_priv *priv)
 			slot1 = IWL_MIN_SLOT_TIME;
 		} else if (!ctx_pan->vif->bss_conf.idle &&
 			   !ctx_pan->vif->bss_conf.assoc) {
-			slot1 = bcnint * 3 - IWL_MIN_SLOT_TIME;
+			slot1 = dtim * bcnint * 3 - IWL_MIN_SLOT_TIME;
 			slot0 = IWL_MIN_SLOT_TIME;
 		}
 	} else if (ctx_pan->vif) {