iwlegacy: allow to enable PS

Power save support was removed from iwlegacy due to possible firmware
crashes problems it cause. I use to plan first inspect code to find
reason of problems, fix them and then allow to enable PS. But
realistically - code inspection will not happen, so let's do it, and
wait for eventual bug reports.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlegacy/3945-mac.c

@@ -3549,7 +3549,8 @@ il3945_setup_mac(struct il_priv *il)
 	hw->vif_data_size = sizeof(struct il_vif_priv);
 
 	/* Tell mac80211 our characteristics */
-	hw->flags = IEEE80211_HW_SIGNAL_DBM | IEEE80211_HW_SPECTRUM_MGMT;
+	hw->flags = IEEE80211_HW_SIGNAL_DBM | IEEE80211_HW_SPECTRUM_MGMT |
+		    IEEE80211_HW_SUPPORTS_PS | IEEE80211_HW_SUPPORTS_DYNAMIC_PS;
 
 	hw->wiphy->interface_modes =
 	    BIT(NL80211_IFTYPE_STATION) | BIT(NL80211_IFTYPE_ADHOC);
@@ -3558,6 +3559,8 @@ il3945_setup_mac(struct il_priv *il)
 	    WIPHY_FLAG_CUSTOM_REGULATORY | WIPHY_FLAG_DISABLE_BEACON_HINTS |
 	    WIPHY_FLAG_IBSS_RSN;
 
+	hw->wiphy->flags &= ~WIPHY_FLAG_PS_ON_BY_DEFAULT;
+
 	hw->wiphy->max_scan_ssids = PROBE_OPTION_MAX_3945;
 	/* we create the 802.11 header and a zero-length SSID element */
 	hw->wiphy->max_scan_ie_len = IL3945_MAX_PROBE_REQUEST - 24 - 2;

drivers/net/wireless/iwlegacy/4965-mac.c

@@ -5712,8 +5712,8 @@ il4965_mac_setup_register(struct il_priv *il, u32 max_probe_length)
 	hw->flags =
 	    IEEE80211_HW_SIGNAL_DBM | IEEE80211_HW_AMPDU_AGGREGATION |
 	    IEEE80211_HW_NEED_DTIM_PERIOD | IEEE80211_HW_SPECTRUM_MGMT |
-	    IEEE80211_HW_REPORTS_TX_ACK_STATUS;
-
+	    IEEE80211_HW_REPORTS_TX_ACK_STATUS | IEEE80211_HW_SUPPORTS_PS |
+	    IEEE80211_HW_SUPPORTS_DYNAMIC_PS;
 	if (il->cfg->sku & IL_SKU_N)
 		hw->flags |=
 		    IEEE80211_HW_SUPPORTS_DYNAMIC_SMPS |