mac80211: fix idle handling sequence

Corey Richardson reported that my idle handling cleanup
(commit fd0f979a1b, "mac80211: simplify idle handling")
broke ath9k_htc. The reason appears to be that it wants
to go out of idle before switching channels. To fix it,
reimplement that sequence.

Reported-by: Corey Richardson <corey@octayn.net>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 3bfe261..58150f8 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -78,7 +78,7 @@
 		ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_TXPOWER);
 }
 
-static u32 ieee80211_idle_off(struct ieee80211_local *local)
+u32 ieee80211_idle_off(struct ieee80211_local *local)
 {
 	if (!(local->hw.conf.flags & IEEE80211_CONF_IDLE))
 		return 0;