cfg80211: fix locking for SIWFREQ

"cfg80211: validate channel settings across interfaces"
contained a locking bug -- in the managed-mode SIWFREQ
call it would end up running into a lock recursion.

This fixes it by not checking that particular interface
for a channel that it needs to stay on, which is as it
should be as that's the interface we're setting the
channel for.

Reported-by: Reinette Chatre <reinette.chatre@intel.com>
Reported-by: Kalle Valo <kalle.valo@iki.fi>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Tested-by: Kalle Valo <kalle.valo@iki.fi>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/chan.c b/net/wireless/chan.c
index bc00c9a..a46ac6c 100644
--- a/net/wireless/chan.c
+++ b/net/wireless/chan.c
@@ -42,13 +42,14 @@
 }
 
 int rdev_set_freq(struct cfg80211_registered_device *rdev,
+		  struct wireless_dev *for_wdev,
 		  int freq, enum nl80211_channel_type channel_type)
 {
 	struct ieee80211_channel *chan;
 	struct ieee80211_sta_ht_cap *ht_cap;
 	int result;
 
-	if (rdev_fixed_channel(rdev, NULL))
+	if (rdev_fixed_channel(rdev, for_wdev))
 		return -EBUSY;
 
 	if (!rdev->ops->set_channel)