mac80211: be more careful in suspend/resume

When suspending with all netdevs down, the device
is stopped but we still call a number of driver
callbacks that the driver might not expect. The
same happens during resume, we might call a few
callbacks without starting the driver. Fix this
by checking open_count around more things and
exiting quickly if it is 0.

Also, while at this I noticed that the coverage
class isn't reprogrammed after resume, so add
that.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/pm.c b/net/mac80211/pm.c
index f87e993..6326d34 100644
--- a/net/mac80211/pm.c
+++ b/net/mac80211/pm.c
@@ -34,6 +34,9 @@
 	struct ieee80211_sub_if_data *sdata;
 	struct sta_info *sta;
 
+	if (!local->open_count)
+		goto suspend;
+
 	ieee80211_scan_cancel(local);
 
 	if (hw->flags & IEEE80211_HW_AMPDU_AGGREGATION) {