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/nl80211.c b/net/wireless/nl80211.c
index 667a87d..a8aaade 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -721,7 +721,7 @@
 		freq = nla_get_u32(info->attrs[NL80211_ATTR_WIPHY_FREQ]);
 
 		mutex_lock(&rdev->devlist_mtx);
-		result = rdev_set_freq(rdev, freq, channel_type);
+		result = rdev_set_freq(rdev, NULL, freq, channel_type);
 		mutex_unlock(&rdev->devlist_mtx);
 		if (result)
 			goto bad_res;