iwlagn: re-enable PS support for iwlagn

The register locking rework addressed the problem where nic
access was obtained incorrectly when PS is enabled.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-core.c

@@ -1382,7 +1382,8 @@ int iwl_setup_mac(struct iwl_priv *priv)
 	hw->flags = IEEE80211_HW_SIGNAL_DBM |
 		    IEEE80211_HW_NOISE_DBM |
 		    IEEE80211_HW_AMPDU_AGGREGATION |
-		    IEEE80211_HW_SPECTRUM_MGMT;
+		    IEEE80211_HW_SPECTRUM_MGMT |
+		    IEEE80211_HW_SUPPORTS_PS;
 	hw->wiphy->interface_modes =
 		BIT(NL80211_IFTYPE_STATION) |
 		BIT(NL80211_IFTYPE_ADHOC);