cfg80211/mac80211: disconnect on suspend

If possible that after suspend, cfg80211 will receive request to
disconnect what require action on interface that was removed during
suspend.

Problem can manifest itself by various warnings similar to below one:

WARNING: at net/mac80211/driver-ops.h:12 ieee80211_bss_info_change_notify+0x2f9/0x300 [mac80211]()
wlan0:  Failed check-sdata-in-driver check, flags: 0x4
Call Trace:
 [<c043e0b3>] warn_slowpath_fmt+0x33/0x40
 [<f83707c9>] ieee80211_bss_info_change_notify+0x2f9/0x300 [mac80211]
 [<f83a660a>] ieee80211_recalc_ps_vif+0x2a/0x30 [mac80211]
 [<f83a6706>] ieee80211_set_disassoc+0xf6/0x500 [mac80211]
 [<f83a9441>] ieee80211_mgd_deauth+0x1f1/0x280 [mac80211]
 [<f8381b36>] ieee80211_deauth+0x16/0x20 [mac80211]
 [<f8261e70>] cfg80211_mlme_down+0x70/0xc0 [cfg80211]
 [<f8264de1>] __cfg80211_disconnect+0x1b1/0x1d0 [cfg80211]

To fix the problem disconnect from any associated network before
suspend. User space is responsible to establish connection again
after resume. This basically need to be done by user space anyway,
because associated stations can go away during suspend (for example
NetworkManager disconnects on suspend and connect on resume by default).

Patch also handle situation when driver refuse to suspend with wowlan
configured and try to suspend again without it.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/core.h b/net/wireless/core.h
index 9a2be8d..d5d06fd 100644
--- a/net/wireless/core.h
+++ b/net/wireless/core.h
@@ -500,6 +500,9 @@
 void cfg80211_update_iface_num(struct cfg80211_registered_device *rdev,
 			       enum nl80211_iftype iftype, int num);
 
+void cfg80211_leave(struct cfg80211_registered_device *rdev,
+		    struct wireless_dev *wdev);
+
 #define CFG80211_MAX_NUM_DIFFERENT_CHANNELS 10
 
 #ifdef CONFIG_CFG80211_DEVELOPER_WARNINGS