mac80211: fix IEEE80211_SDATA_DISCONNECT_RESUME

Since commit 12e7f517029dad819c45eca9ca01fdb9ba57616b,
IEEE80211_SDATA_DISCONNECT_RESUME no longer worked as
it would simply never be tested. Restore a bit of the
code removed there and in 9b7d72c1041ec5b20b24af487a9
to make it work again.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 29620bfc..8a948ca 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -3623,6 +3623,31 @@
 	}
 }
 
+#ifdef CONFIG_PM
+void ieee80211_sta_restart(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
+
+	mutex_lock(&ifmgd->mtx);
+	if (!ifmgd->associated) {
+		mutex_unlock(&ifmgd->mtx);
+		return;
+	}
+
+	if (sdata->flags & IEEE80211_SDATA_DISCONNECT_RESUME) {
+		sdata->flags &= ~IEEE80211_SDATA_DISCONNECT_RESUME;
+		mlme_dbg(sdata, "driver requested disconnect after resume\n");
+		ieee80211_sta_connection_lost(sdata,
+					      ifmgd->associated->bssid,
+					      WLAN_REASON_UNSPECIFIED,
+					      true);
+		mutex_unlock(&ifmgd->mtx);
+		return;
+	}
+	mutex_unlock(&ifmgd->mtx);
+}
+#endif
+
 /* interface setup */
 void ieee80211_sta_setup_sdata(struct ieee80211_sub_if_data *sdata)
 {