cfg80211: stop critical protocol session upon disconnect event

When user-space has started a critical protocol session and a disconnect
event occurs, the rdev::crit_prot_nlportid remains set. This caused a
subsequent NL80211_CMD_CRIT_PROTO_START to fail (-EBUSY). Fix this by
clearing the rdev attribute and call .crit_proto_stop() callback upon
disconnect event.
Reviewed-by: NHante Meuleman <meuleman@broadcom.com>
Reviewed-by: NPieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: NArend van Spriel <arend@broadcom.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>

net/wireless/sme.c

@@ -917,6 +917,12 @@ void __cfg80211_disconnected(struct net_device *dev, const u8 *ie,
 
 	nl80211_send_disconnected(rdev, dev, reason, ie, ie_len, from_ap);
 
+	/* stop critical protocol if supported */
+	if (rdev->ops->crit_proto_stop && rdev->crit_proto_nlportid) {
+		rdev->crit_proto_nlportid = 0;
+		rdev_crit_proto_stop(rdev, wdev);
+	}
+
 	/*
 	 * Delete all the keys ... pairwise keys can't really
 	 * exist any more anyway, but default keys might.