mac80211: add missing channel context release

commit 2a3ba63c235fdcd37f6451bdf4a0c7865a3930cf upstream.

IBSS needs to release the channel context when leaving
but I evidently missed that. Fix it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index 170f9a7..3052672 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -1166,6 +1166,7 @@
 	clear_bit(SDATA_STATE_OFFCHANNEL_BEACON_STOPPED, &sdata->state);
 	ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED |
 						BSS_CHANGED_IBSS);
+	ieee80211_vif_release_channel(sdata);
 	synchronize_rcu();
 	kfree(presp);