cfg80211: Do not warn on same channel at the end of CSA

When cfg80211_update_assoc_bss_entry() is called, there is a
verification that the BSS channel actually changed. As some APs use
CSA also for bandwidth changes, this would result with a kernel
warning.

Fix this by removing the WARN_ON().

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200326150855.96316ada0e8d.I6710376b1b4257e5f4712fc7ab16e2b638d512aa@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/scan.c

@@ -2022,7 +2022,11 @@ void cfg80211_update_assoc_bss_entry(struct wireless_dev *wdev,
 
 	spin_lock_bh(&rdev->bss_lock);
 
-	if (WARN_ON(cbss->pub.channel == chan))
+	/*
+	 * Some APs use CSA also for bandwidth changes, i.e., without actually
+	 * changing the control channel, so no need to update in such a case.
+	 */
+	if (cbss->pub.channel == chan)
 		goto done;
 
 	/* use transmitting bss */